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An Atlantic hurricane, also known as tropical storm or simply hurricane, is a
tropical cyclone A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depend ...
that forms in the Atlantic Ocean, primarily between the months of June and November. A hurricane differs from a
cyclone In meteorology, a cyclone () is a large air mass that rotates around a strong center of low atmospheric pressure, counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere as viewed from above (opposite to an anti ...
or
typhoon A typhoon is a mature tropical cyclone that develops between 180° and 100°E in the Northern Hemisphere. This region is referred to as the Northwestern Pacific Basin, and is the most active tropical cyclone basin on Earth, accounting for a ...
only on the basis of location. A hurricane is a
storm A storm is any disturbed state of the natural environment or the atmosphere An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmos ...
that occurs in the Atlantic Ocean and northeastern Pacific Ocean, a typhoon occurs in the northwestern Pacific Ocean, and a
cyclone In meteorology, a cyclone () is a large air mass that rotates around a strong center of low atmospheric pressure, counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere as viewed from above (opposite to an anti ...
occurs in the South Pacific Ocean or Indian Ocean. Tropical cyclones can be categorized by intensity. ''Tropical storms'' have one-minute maximum sustained winds of at least 39 mph (34 knots, 17 m/s, 63 km/h), while ''hurricanes'' have one-minute maximum sustained winds exceeding 74 mph (64 knots, 33 m/s, 119 km/h). Most North Atlantic
tropical storms A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Dependi ...
and hurricanes form between June 1 and November 30. The United States
National Hurricane Center The National Hurricane Center (NHC) is the division of the United States' NOAA/National Weather Service responsible for tracking and predicting tropical weather systems between the Prime Meridian and the 140th meridian west poleward to the 3 ...
monitors the basin and issues reports, watches, and warnings about
tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...
weather systems for the North Atlantic Basin as one of the Regional Specialized Meteorological Centers for
tropical cyclone A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depend ...
s, as defined by the
World Meteorological Organization The World Meteorological Organization (WMO) is a specialized agency of the United Nations responsible for promoting international cooperation on atmospheric science, climatology, hydrology and geophysics. The WMO originated from the Internati ...
. In recent times, tropical disturbances that reach tropical storm intensity are named from a predetermined list. Hurricanes that result in significant damage or casualties may have their names retired from the list at the request of the affected nations in order to prevent confusion should a subsequent storm be given the same name. On average, in the North Atlantic basin (from 1966 to 2009) 11.3 named storms occur each season, with an average of 6.2 becoming hurricanes and 2.3 becoming major hurricanes ( Category 3 or greater). The
climatological Climatology (from Greek , ''klima'', "place, zone"; and , '' -logia'') or climate science is the scientific study of Earth's climate, typically defined as weather conditions averaged over a period of at least 30 years. This modern field of stud ...
peak of activity is around September 10 each season. In March 2004, Catarina was the first hurricane-intensity tropical cyclone to be recorded in the Southern Atlantic Ocean. Since 2011, the
Brazilian Navy Hydrographic Center ) , colors= Blue and White (color), white , colors_label= Colors , march= "s:Cisne Branco, Cisne Branco" ( en, "White Swan") (same name as training ship ''Cisne Branco'' , mascot= , equipment= 1 helicopter carrier, multipurpose aircraft carrier7 ...
has started to use the same scale as the North Atlantic Ocean for tropical cyclones in the South Atlantic Ocean and assign names to those which reach .


Steering factors

Tropical cyclone A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depend ...
s are steered by the surrounding flow throughout the depth of the
troposphere The troposphere is the first and lowest layer of the atmosphere of the Earth, and contains 75% of the total mass of the planetary atmosphere, 99% of the total mass of water vapour and aerosols, and is where most weather phenomena occur. From ...
(the atmospheric from the surface to about high).
Neil Frank Neil Laverne Frank (born September 11, 1931) is an American meteorologist and former director of the National Hurricane Center (NHC) in Florida. He was instrumental in advancing both the scientific and informational aspects of hurricane forecasti ...
, former director of the United States
National Hurricane Center The National Hurricane Center (NHC) is the division of the United States' NOAA/National Weather Service responsible for tracking and predicting tropical weather systems between the Prime Meridian and the 140th meridian west poleward to the 3 ...
, used the analogies such as "a leaf carried along in a stream" or a "brick moving through a river of air" to describe the way atmospheric flow affects the path of a hurricane across the ocean. Specifically, air flow around
high pressure In science and engineering the study of high pressure examines its effects on materials and the design and construction of devices, such as a diamond anvil cell, which can create high pressure. By ''high pressure'' is usually meant pressures of th ...
systems and toward
low-pressure area In meteorology, a low-pressure area, low area or low is a region where the atmospheric pressure is lower than that of surrounding locations. Low-pressure areas are commonly associated with inclement weather (such as cloudy, windy, with possible ...
s influences hurricane tracks. In the tropical latitudes, tropical storms and hurricanes generally move westward with a slight tendency toward the north, under the influence of the ''
subtropical ridge The horse latitudes are the latitudes about 30 degrees north and south of the Equator. They are characterized by sunny skies, calm winds, and very little precipitation. They are also known as Subtropics, subtropical ridges, or highs. It is a h ...
'', a high-pressure system that usually extends east–west across the subtropics. South of the subtropical ridge, surface easterly winds (blowing from east to west) prevail. If the subtropical ridge is weakened by an upper
trough Trough may refer to: In science * Trough (geology), a long depression less steep than a trench * Trough (meteorology), an elongated region of low atmospheric pressure * Trough (physics), the lowest point on a wave * Trough level (medicine), the l ...
, a tropical cyclone may turn poleward and then ''recurve'', or curve back toward the northeast into the main belt of the Westerlies. Poleward (north) of the subtropical ridge, westerly winds prevail and generally steer tropical cyclones that reach northern latitudes toward the east. The
westerlies The westerlies, anti-trades, or prevailing westerlies, are prevailing winds from the west toward the east in the middle latitudes between 30 and 60 degrees latitude. They originate from the high-pressure areas in the horse latitudes and trend to ...
also steer
extratropical cyclone Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are low-pressure areas which, along with the anticyclones of high-pressure areas, drive the weather over much of the Earth. Extratropical cyclones are capable of ...
s with their cold and warm fronts from west to east.


Intensity

Generally speaking, the intensity of a tropical cyclone is determined by either the storm's
maximum sustained wind The maximum sustained wind associated with a tropical cyclone is a common indicator of the intensity of the storm. Within a mature tropical cyclone, it is found within the eyewall at a distance defined as the radius of maximum wind, or RMW. Unl ...
s or lowest
barometric pressure Atmospheric pressure, also known as barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1013.25 millibars, 7 ...
. The following table lists the most intense Atlantic hurricanes in terms of their lowest barometric pressure. In terms of wind speed,
Hurricane Allen Hurricane Allen was a rare and extremely powerful Cape Verde hurricane that affected the Caribbean, eastern and northern Mexico, and southern Texas in August 1980. The first named storm and second tropical cyclone of the 1980 Atlantic hurricane ...
(in
1980 Events January * January 4 – U.S. President Jimmy Carter proclaims a grain embargo against the USSR with the support of the European Commission. * January 6 – Global Positioning System time epoch begins at 00:00 UTC. * January 9 – ...
) was the strongest Atlantic tropical cyclone on record, with maximum sustained winds of . However, these measurements are suspect since instrumentation used to document wind speeds at the time would likely succumb to winds of such intensity. Nonetheless, their central pressures are low enough to rank them among the strongest recorded Atlantic hurricanes. Owing to their intensity, the strongest Atlantic hurricanes have all attained Category 5 classification.
Hurricane Opal Hurricane Opal was a large and powerful Category 4 hurricane that caused severe and extensive damage along the northern Gulf Coast of the United States in October 1995. The fifteenth named storm, ninth hurricane and strongest tropical cyclon ...
, the strongest Category 4 hurricane recorded, intensified to reach a minimum pressure of , a pressure typical of Category 5 hurricanes.
Hurricane Wilma Hurricane Wilma was an extremely intense and destructive Atlantic hurricane which was the most intense storm of its kind and the second-most intense tropical cyclone recorded in the Western Hemisphere, after Hurricane Patricia in 2015. Part o ...
is the strongest Atlantic hurricane recorded, after reaching an intensity of in October 2005; this also made Wilma the strongest tropical cyclone worldwide outside of the
West Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...
, where seven tropical cyclones have been recorded to intensify to lower pressures. However, this was later superseded by
Hurricane Patricia Hurricane Patricia was the strongest tropical cyclone on record worldwide in terms of wind speed and the second-most intense on record worldwide in terms of pressure, behind Typhoon Tip in 1979, with a minimum atmospheric pressure of 872 mbar ( ...
in
2015 File:2015 Events Collage new.png, From top left, clockwise: Civil service in remembrance of November 2015 Paris attacks; Germanwings Flight 9525 was purposely crashed into the French Alps; the rubble of residences in Kathmandu following the Apri ...
in the east Pacific, which had a pressure reading of 872 mbar. Preceding Wilma is
Hurricane Gilbert Hurricane Gilbert was the second most intense tropical cyclone on record in the Atlantic basin in terms of barometric pressure, only behind Hurricane Wilma in 2005. An extremely powerful tropical cyclone that formed during the 1988 Atlantic hurr ...
, which had also held the record for most intense Atlantic hurricane for 17 years. The
1935 Labor Day hurricane The Great Labor Day Hurricane of 1935 was the most intense Atlantic hurricane to make landfall on record by pressure, with winds of up to 185 mph (297 km/h). The fourth tropical cyclone, third tropical storm, second hurricane, and se ...
, with a pressure of 892 mbar (hPa; ), is the third strongest Atlantic hurricane and the strongest documented tropical cyclone prior to 1950. Since the measurements taken during Wilma and Gilbert were documented using
dropsonde A dropsonde is an expendable weather reconnaissance device created by the National Center for Atmospheric Research (NCAR), designed to be dropped from an aircraft at altitude over water to measure (and therefore track) storm conditions as the devi ...
, this pressure remains the lowest measured over land.
Hurricane Rita Hurricane Rita was the most intense tropical cyclone on record in the Gulf of Mexico and the fourth-most intense Atlantic hurricane ever recorded. Part of the record-breaking 2005 Atlantic hurricane season, which included three of the top ten L ...
is the fourth strongest Atlantic hurricane in terms of barometric pressure and one of three tropical cyclones from 2005 on the list, with the others being Wilma and
Katrina Katrina or Katrine may refer to: People * Katrina (given name) * Katrine (given name) Meteorology * List of storms named Katrina, a list of tropical cyclones designated as Katrina ** Hurricane Katrina, an exceptionally powerful Atlantic hurrican ...
at first and seventh respectively. However, with a barometric pressure of , Rita is the strongest tropical cyclone ever recorded in the
Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...
.
Mitch Mitch is a short form of the masculine given name Mitchell. It is also sometimes a nickname, usually for a person with the surname Mitchell. It may refer to: People * Mitch Altman (born 1956), hacker and inventor * Mitch Apau (born 1990), Dutc ...
and
Dean Dean may refer to: People * Dean (given name) * Dean (surname), a surname of Anglo-Saxon English origin * Dean (South Korean singer), a stage name for singer Kwon Hyuk * Dean Delannoit, a Belgian singer most known by the mononym Dean Titles * ...
share intensities for the eighth strongest Atlantic hurricane at . The tenth place for most intense Atlantic tropical cyclone is
Hurricane Maria Hurricane Maria was a deadly Saffir–Simpson scale#Category 5, Category 5 Tropical cyclone, hurricane that devastated the northeastern Caribbean in September 2017, particularly Dominica, Saint Croix, and Puerto Rico. It is regarded as the wo ...
listed to have deepened to a pressure as low as Many of the strongest recorded tropical cyclones weakened prior to their eventual
landfall Landfall is the event of a storm moving over land after being over water. More broadly, and in relation to human travel, it refers to 'the first land that is reached or seen at the end of a journey across the sea or through the air, or the fact ...
or demise. However, three of the storms remained intense enough at landfall to be considered some of the strongest landfalling hurricanes – three of the ten hurricanes on the list constitute the three most intense Atlantic landfalls in recorded history. The 1935 Labor Day hurricane made landfall at peak intensity, making it the most intense Atlantic landfall. Though it weakened slightly before its eventual landfall on the
Yucatán Peninsula The Yucatán Peninsula (, also , ; es, Península de Yucatán ) is a large peninsula in southeastern Mexico and adjacent portions of Belize and Guatemala. The peninsula extends towards the northeast, separating the Gulf of Mexico to the north ...
, Hurricane Gilbert maintained a pressure of at landfall, as did Camille, making their landfalls tied as the second strongest. Similarly, Hurricane Dean made landfall on the peninsula, though it did so at peak intensity and with a higher barometric pressure; its landfall marked the fourth strongest in Atlantic hurricane history.


Climatology

Climatology Climatology (from Greek , ''klima'', "place, zone"; and , '' -logia'') or climate science is the scientific study of Earth's climate, typically defined as weather conditions averaged over a period of at least 30 years. This modern field of stud ...
serves to characterize the general properties of an average season and can be used as one of many other tools for making forecasts. Most storms form in warm waters several hundred miles north of the
equator The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can als ...
near the
Intertropical convergence zone The Intertropical Convergence Zone (ITCZ ), known by sailors as the doldrums or the calms because of its monotonous windless weather, is the area where the northeast and the southeast trade winds converge. It encircles Earth near the thermal e ...
from
tropical wave A tropical wave (also called easterly wave, tropical easterly wave, and African easterly wave), in and around the Atlantic Ocean, is a type of atmospheric trough, an elongated area of relatively low air pressure, oriented north to south, which ...
s. The
Coriolis force In physics, the Coriolis force is an inertial or fictitious force that acts on objects in motion within a frame of reference that rotates with respect to an inertial frame. In a reference frame with clockwise rotation, the force acts to the ...
is usually too weak to initiate sufficient rotation near the equator. Storms frequently form in the warm waters of the
Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...
, the Caribbean, and the tropical Atlantic Ocean as far east as the
Cape Verde , national_anthem = () , official_languages = Portuguese , national_languages = Cape Verdean Creole , capital = Praia , coordinates = , largest_city = capital , demonym ...
Islands, the origin of strong and long-lasting Cape Verde-type hurricanes. Systems may also strengthen over the
Gulf Stream The Gulf Stream, together with its northern extension the North Atlantic Current, North Atlantic Drift, is a warm and swift Atlantic Ocean, Atlantic ocean current that originates in the Gulf of Mexico and flows through the Straits of Florida a ...
off the coast of the eastern United States, wherever water temperatures exceed . Although most storms are found within tropical latitudes, occasionally storms will form further north and east from disturbances other than tropical waves such as
cold front A cold front is the leading edge of a cooler mass of air at ground level that replaces a warmer mass of air and lies within a pronounced surface trough of low pressure. It often forms behind an extratropical cyclone (to the west in the Norther ...
s and upper-level lows. These are known as baroclinically induced tropical cyclones. There is a strong correlation between Atlantic hurricane activity in the tropics and the presence of an
El Niño El Niño (; ; ) is the warm phase of the El Niño–Southern Oscillation (ENSO) and is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific (approximately between the International Date L ...
or
La Niña La Niña (; ) is an oceanic and atmospheric phenomenon that is the colder counterpart of as part of the broader El Niño–Southern Oscillation (ENSO) climate pattern. The name ''La Niña'' originates from Spanish for "the girl", by an ...
in the Pacific Ocean. El Niño events increase the wind shear over the Atlantic, producing a less-favorable environment for formation and decreasing tropical activity in the Atlantic basin. Conversely, La Niña causes an increase in activity due to a decrease in wind shear. According to the
Azores High The Azores High also known as North Atlantic (Subtropical) High/Anticyclone or the Bermuda-Azores High, is a large subtropical semi-permanent centre of high atmospheric pressure typically found south of the Azores in the Atlantic Ocean, at the Hor ...
hypothesis by Kam-biu Liu, an anti-phase pattern is expected to exist between the
Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...
coast and the North American Atlantic coast. During the quiescent periods (3000–1400 BC, and 1000 AD to present), a more northeasterly position of the Azores High would result in more hurricanes being steered toward the Atlantic coast. During the hyperactive period (1400 BC to 1000 AD), more hurricanes were steered towards the Gulf coast as the Azores High was shifted to a more southwesterly position near the Caribbean. Such a displacement of the Azores High is consistent with paleoclimatic evidence that shows an abrupt onset of a drier climate in
Haiti Haiti (; ht, Ayiti ; French: ), officially the Republic of Haiti (); ) and formerly known as Hayti, is a country located on the island of Hispaniola in the Greater Antilles archipelago of the Caribbean Sea, east of Cuba and Jamaica, and ...
around 3200 14C years BP, and a change towards more humid conditions in the
Great Plains The Great Plains (french: Grandes Plaines), sometimes simply "the Plains", is a broad expanse of flatland in North America. It is located west of the Mississippi River and east of the Rocky Mountains, much of it covered in prairie, steppe, an ...
during the late-
Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...
as more moisture was pumped up the
Mississippi Valley The Mississippi River is the List of longest rivers of the United States (by main stem), second-longest river and chief river of the second-largest Drainage system (geomorphology), drainage system in North America, second only to the Hudson B ...
through the Gulf coast. Preliminary data from the northern Atlantic coast seem to support the Azores High hypothesis. A 3000-year proxy record from a coastal lake in
Cape Cod Cape Cod is a peninsula extending into the Atlantic Ocean from the southeastern corner of mainland Massachusetts, in the northeastern United States. Its historic, maritime character and ample beaches attract heavy tourism during the summer mont ...
suggests that hurricane activity has increased significantly during the past 500–1000 years, just as the Gulf coast was amid a quiescent period of the last millennium.


Seasonal variation

Climatologically speaking, approximately 97 percent of
tropical cyclones A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depend ...
that form in the North Atlantic
develop Develop or DEVELOP may refer to: * ''Develop'' (magazine), a trade publication for the video game industry * ''Develop'' (Apple magazine), a technical magazine formerly published by Apple Computer * Develop (chess), moving a piece from its origina ...
between the dates of June 1 and November 30 – dates which delimit the modern-day Atlantic hurricane season. Though the beginning of the annual hurricane season has historically remained the same, the official end of the hurricane season has shifted from its initial date of October 31. Regardless, on average once every few years a tropical cyclone develops outside the limits of the season; As of September 2021, there have been 88 tropical cyclones in the off-season, with the most recent being Tropical Storm Ana in May 2021. The first tropical cyclone of the 1938 Atlantic hurricane season, which formed on January 3, became the earliest forming tropical storm and hurricane after reanalysis concluded on the storm in December 2012.
Hurricane Able The name Able has been used for three tropical cyclones in the Atlantic Ocean. *Hurricane Able (1950), a Category 3 hurricane that ultimately hit Nova Scotia as a tropical storm *Hurricane Able (1951), an early-season Category 1 hurricane ...
in
1951 Events January * January 4 – Korean War: Third Battle of Seoul – Chinese and North Korean forces capture Seoul for the second time (having lost the Second Battle of Seoul in September 1950). * January 9 – The Government of the United ...
was initially thought to be the earliest forming major hurricane – a tropical cyclone with winds exceeding  – however following post-storm analysis it was determined that Able only reached Category 1 strength which made
Hurricane Alma The name Alma has been used to name 11 tropical cyclones worldwide: 5 in the North Atlantic Ocean, 5 in the Eastern Pacific Ocean, and 1 in the Western Pacific Ocean. In the Atlantic: * Tropical Storm Alma (1958), made landfall in northeastern Mexi ...
of
1966 Events January * January 1 – In a coup, Colonel Jean-Bédel Bokassa takes over as military ruler of the Central African Republic, ousting President David Dacko. * January 3 – 1966 Upper Voltan coup d'état: President Maurice Yaméogo i ...
the new record holder; as it became a major hurricane on June 8. Though it developed within the bounds of the Atlantic hurricane season,
Hurricane Audrey Hurricane Audrey was one of the deadliest tropical cyclones in U.S. history, killing at least 416 people in its devastation of the southwestern Louisiana coast in 1957. Along with Hurricane Alex in 2010, it was also the strongest June hur ...
in
1957 1957 ( MCMLVII) was a common year starting on Tuesday of the Gregorian calendar, the 1957th year of the Common Era (CE) and ''Anno Domini'' (AD) designations, the 957th year of the 2nd millennium, the 57th year of the 20th century, and the 8th y ...
became the earliest developing Category 4 hurricane on record after it reached the intensity on June 27. However, reanalysis from 1956 to 1960 by NOAA downgraded Audrey to a Category 3, making Hurricane Dennis of 2005 the earliest Category 4 on record on July 8, 2005. The earliest-forming Category 5 hurricane, Emily, reached the highest intensity on the Saffir–Simpson hurricane wind scale on July 17, 2005. Though the official end of the Atlantic hurricane season occurs on November 30, the dates of October 31 and November 15 have also historically marked the official end date for the hurricane season. December, the only month of the year after the hurricane season, has featured the cyclogenesis of fourteen tropical cyclones.
Tropical Storm Zeta The name Zeta has been used for two tropical cyclones in the Atlantic Ocean. * Tropical Storm Zeta (2005), post-season storm that formed on December 30, and continued into January 2006 * Hurricane Zeta Hurricane Zeta was a late-season ma ...
in 2005 was the latest tropical cyclone to attain tropical storm intensity as it did so on December 30. However, the second Hurricane Alice in
1954 Events January * January 1 – The Soviet Union ceases to demand war reparations from West Germany. * January 3 – The Italian broadcaster RAI officially begins transmitting. * January 7 – Georgetown-IBM experiment: The fir ...
was the latest forming tropical cyclone to attain hurricane intensity. Both Zeta and Alice were the only two storms to exist in two calendar years – the former from 1954 to 1955 and the latter from 2005 to 2006. No storms have been recorded to exceed Category 1 hurricane intensity in December. In
1999 File:1999 Events Collage.png, From left, clockwise: The funeral procession of King Hussein of Jordan in Amman; the 1999 İzmit earthquake kills over 17,000 people in Turkey; the Columbine High School massacre, one of the first major school shootin ...
,
Hurricane Lenny Hurricane Lenny was the strongest November Atlantic hurricane since the 1932 Cuba hurricane. It was the twelfth tropical storm, eighth hurricane, and record-breaking fifth Category 4 hurricane in the 1999 Atlantic hurricane season. Lenny ...
reached Category 4 intensity on November 17 as it took an unprecedented west to east track across the Caribbean; its intensity made it the latest developing Category 4 hurricane, though this was well within the bounds of the hurricane season.
Hurricane Hattie Hurricane Hattie was one of the strongest and deadliest tropical cyclones of the 1961 Atlantic hurricane season, reaching a peak intensity as a Category5 hurricane. The ninth tropical storm, seventh hurricane, fifth major hurricane, and seco ...
(October 27 – November 1, 1961) was initially thought to have been the latest forming Category 5 hurricane ever documented, though reanalysis indicated that a devastating hurricane in
1932 Events January * January 4 – The British authorities in India arrest and intern Mahatma Gandhi and Vallabhbhai Patel. * January 9 – Sakuradamon Incident (1932), Sakuradamon Incident: Korean nationalist Lee Bong-chang fails in his effort ...
reached such an intensity at a later date. Consequently, this made the hurricane the latest developing tropical cyclone to reach all four Saffir–Simpson hurricane wind scale classifications past Category 1 intensity. Although 2020's
Hurricane Iota Hurricane Iota was a devastating late-season Category 4 hurricane, Category 4 Atlantic hurricane which caused severe damage to areas of Central America already devastated by Hurricane Eta just less than two weeks prior. The 31st and final trop ...
would go on to surpass the 1932 hurricane in both of these categories.


June

The beginning of the hurricane season is most closely related to the timing of increases in
sea surface temperatures Sea surface temperature (SST), or ocean surface temperature, is the ocean temperature close to the surface. The exact meaning of ''surface'' varies according to the measurement method used, but it is between and below the sea surface. Air masse ...
,
convective instability In meteorology, convective instability or stability of an air mass refers to its ability to resist vertical motion. A ''stable'' atmosphere makes vertical movement difficult, and small vertical disturbances dampen out and disappear. In an ''unst ...
, and other thermodynamic factors.William M. Gray and Philip J. Klotzbach
SUMMARY OF 2005 ATLANTIC TROPICAL CYCLONE ACTIVITY AND VERIFICATION OF AUTHOR’S SEASONAL AND MONTHLY FORECASTS.
Retrieved on 2006-10-28.
Although June marks the beginning of the hurricane season, generally little activity occurs during the month with an average of 1
tropical cyclone A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depend ...
every 2 years. Tropical systems usually form in the
Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...
or off the east coast of the United States. Since 1851, a total of 81 tropical storms and hurricanes formed in the month of June. During this period, two of these systems developed in the deep tropics east of the Lesser Antilles.USDC and NOAA (2009) Historical Climatology Series 6-2 ''Tropical Cyclones of the North Atlantic Ocean 1851–2006'' pp. ''212'' Since 1870, three major hurricanes have formed during June, most notably
Hurricane Audrey Hurricane Audrey was one of the deadliest tropical cyclones in U.S. history, killing at least 416 people in its devastation of the southwestern Louisiana coast in 1957. Along with Hurricane Alex in 2010, it was also the strongest June hur ...
in
1957 1957 ( MCMLVII) was a common year starting on Tuesday of the Gregorian calendar, the 1957th year of the Common Era (CE) and ''Anno Domini'' (AD) designations, the 957th year of the 2nd millennium, the 57th year of the 20th century, and the 8th y ...
. Audrey attained an intensity greater than that of any Atlantic tropical cyclone during June or July until Hurricanes Dennis and Emily of 2005.USDC and NOAA (2009) Historical Climatology Series 6-2 ''Tropical Cyclones of the North Atlantic Ocean 1851–2006'' pp. ''27'' The easternmost forming storm during June, Tropical Storm Ana in 1979, formed at 45°W.


July

Not much tropical activity occurs during the month of July, but the majority of hurricane seasons see the formation of one
tropical cyclone A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depend ...
during July. From an average of Atlantic tropical cyclone seasons from 1944 to 1996, the first tropical storm in half of the seasons occurred by 11 July, and a second formed by 8 August. Formation usually occurs in the eastern Caribbean around the
Lesser Antilles The Lesser Antilles ( es, link=no, Antillas Menores; french: link=no, Petites Antilles; pap, Antias Menor; nl, Kleine Antillen) are a group of islands in the Caribbean Sea. Most of them are part of a long, partially volcanic island arc betwe ...
, in the northern and eastern parts of the
Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...
, in the vicinity of the northern
Bahamas The Bahamas (), officially the Commonwealth of The Bahamas, is an island country within the Lucayan Archipelago of the West Indies in the Atlantic Ocean, North Atlantic. It takes up 97% of the Lucayan Archipelago's land area and is home to ...
, and off the coast of
The Carolinas The Carolinas are the U.S. states of North Carolina and South Carolina, considered collectively. They are bordered by Virginia to the north, Tennessee to the west, and Georgia to the southwest. The Atlantic Ocean is to the east. Combining Nort ...
and
Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth ar ...
over the
Gulf Stream The Gulf Stream, together with its northern extension the North Atlantic Current, North Atlantic Drift, is a warm and swift Atlantic Ocean, Atlantic ocean current that originates in the Gulf of Mexico and flows through the Straits of Florida a ...
. Storms travel westward through the Caribbean and then either move towards the north and curve near the eastern coast of the United States or stay on a north-westward track and enter the
Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...
. Since 1851, a total of 105 tropical storms have formed during the month of July.USDC and NOAA (2009) Historical Climatology Series 6-2 ''Tropical Cyclones of the North Atlantic Ocean 1851–2006'' pp. ''213'' Since 1870, ten of these storms reached major hurricane intensity. Only
Hurricane Emily The name Emily has been used for fourteen tropical cyclones worldwide, seven in the Atlantic Ocean, five in the Eastern Pacific Ocean, and two in the Southern Hemisphere. In the Atlantic: * Hurricane Emily (1981) – crossed Bermuda *Hurricane Emi ...
of
2005 File:2005 Events Collage V2.png, From top left, clockwise: Hurricane Katrina in the Gulf of Mexico; the Funeral of Pope John Paul II is held in Vatican City; "Me at the zoo", the first video ever to be uploaded to YouTube; Eris was discovered in ...
, the strongest July tropical cyclone in the Atlantic basin, attained Category 5 hurricane status during July, making it the earliest Category 5 hurricane on record.USDC and NOAA (2009) Historical Climatology Series 6-2 ''Tropical Cyclones of the North Atlantic Ocean 1851–2006'' pp. ''200'' The easternmost forming storm and longest lived during the month of July,
Hurricane Bertha The name Bertha has been used for ten tropical cyclones in the Atlantic Ocean. * Tropical Storm Bertha (1957), a moderate tropical storm that threatened areas devastated by Hurricane Audrey two months earlier, but did not become a hurricane and ca ...
in
2008 File:2008 Events Collage.png, From left, clockwise: Lehman Brothers went bankrupt following the Subprime mortgage crisis; Cyclone Nargis killed more than 138,000 in Myanmar; A scene from the opening ceremony of the 2008 Summer Olympics in Beijing; ...
, formed at 22.9°W and lasted 17 days.USDC and NOAA (2009) Historical Climatology Series 6-2 ''Tropical Cyclones of the North Atlantic Ocean 1851–2006'' pp. ''203''


August

Decrease in wind shear from July to August contributes to a significant increase of tropical activity.Anantha R. Aiyyer
Climatology of Vertical Wind Shear Over the Tropical Atlantic.
Retrieved on 2006-10-28.
An average of 2.8 Atlantic tropical storms develop annually in August. On average, four named tropical storms, including one hurricane, occur by August 30, and the first intense hurricane develops by 4 September.


September

The peak of the hurricane season occurs in September and corresponds with low
wind shear Wind shear (or windshear), sometimes referred to as wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical or horizontal ...
and the warmest
sea surface temperature Sea surface temperature (SST), or ocean surface temperature, is the ocean temperature close to the surface. The exact meaning of ''surface'' varies according to the measurement method used, but it is between and below the sea surface. Air mass ...
s. The month of September sees an average of 3 storms a year. By 24 September, the average Atlantic season features 7 named tropical storms, including 4 hurricanes. In addition, two major hurricanes occur on average by 28 September. Relatively few tropical cyclones make landfall at these intensities.


October

The favorable conditions found during September begin to decay in October. The main reason for the decrease in activity is increasing
wind shear Wind shear (or windshear), sometimes referred to as wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical or horizontal ...
, although
sea surface temperature Sea surface temperature (SST), or ocean surface temperature, is the ocean temperature close to the surface. The exact meaning of ''surface'' varies according to the measurement method used, but it is between and below the sea surface. Air mass ...
s are also cooler than in September. Activity falls markedly with 1.8 cyclones developing on average despite a climatological secondary peak around 20 October. By 21 October, the average season features 9 named storms with 5 hurricanes. A third major hurricane occurs after 28 September in half of all Atlantic tropical cyclone seasons. In contrast to mid-season activity, the mean locus of formation shifts westward to the Caribbean and Gulf of Mexico, reversing the eastward progression of June through August.


November

Wind shear from
westerlies The westerlies, anti-trades, or prevailing westerlies, are prevailing winds from the west toward the east in the middle latitudes between 30 and 60 degrees latitude. They originate from the high-pressure areas in the horse latitudes and trend to ...
increases substantially through November, generally preventing cyclone formation. On average, one tropical storm forms during every other November. On rare occasions, a major hurricane occurs. The few intense hurricanes in November include Hurricane "Cuba" in late October and early November 1932 (the strongest November hurricane on record peaking as a Category 5 hurricane),
Hurricane Lenny Hurricane Lenny was the strongest November Atlantic hurricane since the 1932 Cuba hurricane. It was the twelfth tropical storm, eighth hurricane, and record-breaking fifth Category 4 hurricane in the 1999 Atlantic hurricane season. Lenny ...
in mid-November 1999, Hurricane Kate in late November 1985 which was the latest major hurricane formation on record until
Hurricane Otto Hurricane Otto was a strong late-season tropical cyclone that impacted parts of Central America in November 2016. It was the first Atlantic hurricane since Cesar–Douglas in 1996 to survive the crossover from the Atlantic Ocean to the Pacific ...
(a category 3 storm) of the 2016 hurricane season.
Hurricane Paloma Hurricane Paloma was the seventh most intense November Atlantic hurricane on record. It was the sixteenth tropical storm, eighth hurricane and fifth major hurricane of the 2008 Atlantic hurricane season. A late-season hurricane, it set several r ...
was a very potent category 4 storm that made landfall in Cuba in early November 2008, and
Hurricane Eta Hurricane Eta was a deadly and erratic Saffir-Simpson scale, Category 4 hurricane that devastated parts of Central America in early November 2020. The record-tying twenty-eighth Tropical cyclone naming, named storm, thirteenth hurricane, and s ...
strengthened into a Category 4 hurricane in early November 2020, becoming the second-most intense tropical cyclone in November, then made landfall in Central America. In that same year
Hurricane Iota Hurricane Iota was a devastating late-season Category 4 hurricane, Category 4 Atlantic hurricane which caused severe damage to areas of Central America already devastated by Hurricane Eta just less than two weeks prior. The 31st and final trop ...
strengthened to a Category 4 hurricane on November 16, becoming the second most intense hurricane in November since
1933 Events January * January 11 – Sir Charles Kingsford Smith makes the first commercial flight between Australia and New Zealand. * January 17 – The United States Congress votes in favour of Philippines independence, against the wis ...
.


December to May

Although the hurricane season is defined as beginning on June 1 and ending on November 30, there have been several off-season storms. Since 1870, there have been 32 off-season cyclones, 18 of which occurred in May. In the same time span, nine storms formed in December, two in April, and one each in January, February and March. During four years (
1887 Events January–March * January 11 – Louis Pasteur's anti-rabies treatment is defended in the Académie Nationale de Médecine, by Dr. Joseph Grancher. * January 20 ** The United States Senate allows the Navy to lease Pearl Har ...
,
1953 Events January * January 6 – The Asian Socialist Conference opens in Rangoon, Burma. * January 12 – Estonian émigrés found a Estonian government-in-exile, government-in-exile in Oslo. * January 14 ** Marshal Josip Broz Tito i ...
,USDC and NOAA (2009) Historical Climatology Series 6-2 ''Tropical Cyclones of the North Atlantic Ocean 1851–2006'' pp. ''148''
2003 File:2003 Events Collage.png, From top left, clockwise: The crew of STS-107 perished when the Space Shuttle Columbia disintegrated during reentry into Earth's atmosphere; SARS became an epidemic in China, and was a precursor to SARS-CoV-2; A des ...
, and
2007 File:2007 Events Collage.png, From top left, clockwise: Steve Jobs unveils Apple's first iPhone; TAM Airlines Flight 3054 overruns a runway and crashes into a gas station, killing almost 200 people; Former Pakistani Prime Minister of Pakistan, Pr ...
), tropical cyclones formed in the North Atlantic Ocean both during or before May and during December.USDC and NOAA (2009) Historical Climatology Series 6-2 ''Tropical Cyclones of the North Atlantic Ocean 1851–2006'' pp. ''202'' In 1887, four storms occurred outside the season, the most in a single year.USDC and NOAA (2009) Historical Climatology Series 6-2 ''Tropical Cyclones of the North Atlantic Ocean 1851–2006'' pp. ''82'' High vertical wind shear and low
sea surface temperature Sea surface temperature (SST), or ocean surface temperature, is the ocean temperature close to the surface. The exact meaning of ''surface'' varies according to the measurement method used, but it is between and below the sea surface. Air mass ...
s generally preclude tropical cyclone formation during the off-season. Tropical cyclones have formed in all months. Four tropical cyclones existed during the month of January, two of which formed during late December: the second Hurricane Alice in 1954/1955, and
Tropical Storm Zeta The name Zeta has been used for two tropical cyclones in the Atlantic Ocean. * Tropical Storm Zeta (2005), post-season storm that formed on December 30, and continued into January 2006 * Hurricane Zeta Hurricane Zeta was a late-season ma ...
in 2005/2006. The only two hurricanes to form in January are a Category 1 hurricane in the 1938 season, and Hurricane Alex in the 2016 season. A subtropical storm in January also began the
1978 Atlantic hurricane season The 1978 Atlantic hurricane season was the last Atlantic hurricane season to use an all-female naming list. The season officially began on June 1, and ended on November 30. It was an above average season due to a subsiding El Niño. The ...
. No major hurricanes have occurred in the off-season.USDC and NOAA (2009) Historical Climatology Series 6-2 ''Tropical Cyclones of the North Atlantic Ocean 1851–2006'' pp. ''146''


Extremes

* The season in which the most tropical storms formed on record is the
2020 Atlantic hurricane season The 2020 Atlantic hurricane season featured a total of 31 tropical or subtropical cyclones, making it the most active Atlantic hurricane season on record. All but one cyclone became a named storm. Of the 30 named storms, 14 deve ...
(30). However,
2005 File:2005 Events Collage V2.png, From top left, clockwise: Hurricane Katrina in the Gulf of Mexico; the Funeral of Pope John Paul II is held in Vatican City; "Me at the zoo", the first video ever to be uploaded to YouTube; Eris was discovered in ...
was the one in which the most hurricanes formed on record (15). * The
2005 Atlantic hurricane season The 2005 Atlantic hurricane season was the most active Atlantic hurricane season in history, until the record was broken 15 years later in 2020. The season broke numerous records at the time, with 28 tropical or subtropical storms recorded. ...
has had the most major hurricanes on record (7), also tied with 2020. The 1950 Atlantic hurricane season and 1961 Atlantic hurricane season were once thought to have 8 and 7 respectively, but re-analysis showed that several storms during both seasons were weaker than thought, and thus the records are now held by the
2005 File:2005 Events Collage V2.png, From top left, clockwise: Hurricane Katrina in the Gulf of Mexico; the Funeral of Pope John Paul II is held in Vatican City; "Me at the zoo", the first video ever to be uploaded to YouTube; Eris was discovered in ...
and
2020 2020 was heavily defined by the COVID-19 pandemic, which led to global Social impact of the COVID-19 pandemic, social and Economic impact of the COVID-19 pandemic, economic disruption, mass cancellations and postponements of events, COVID- ...
seasons. * The least active season on record since 1946 (when the database is considered more reliable) was the
1983 Atlantic hurricane season The 1983 Atlantic hurricane season was the least active Atlantic hurricane season since 1930. The season officially began on June 1, 1983, and lasted until November 30, 1983. These dates conventionally delimit the period of each year when most ...
, with four tropical storms, two hurricanes, and one major hurricane. Overall, the 1914 Atlantic hurricane season remains the least active, with only one documented storm. * The most intense hurricane (by barometric pressure) on record in the North Atlantic basin was
Hurricane Wilma Hurricane Wilma was an extremely intense and destructive Atlantic hurricane which was the most intense storm of its kind and the second-most intense tropical cyclone recorded in the Western Hemisphere, after Hurricane Patricia in 2015. Part o ...
(
2005 File:2005 Events Collage V2.png, From top left, clockwise: Hurricane Katrina in the Gulf of Mexico; the Funeral of Pope John Paul II is held in Vatican City; "Me at the zoo", the first video ever to be uploaded to YouTube; Eris was discovered in ...
) (882
mbar The bar is a metric unit of pressure, but not part of the International System of Units (SI). It is defined as exactly equal to 100,000  Pa (100 kPa), or slightly less than the current average atmospheric pressure on Earth at sea leve ...
). * The largest hurricane (in gale diameter winds) on record to form in the North Atlantic was
Hurricane Sandy Hurricane Sandy (unofficially referred to as ''Superstorm Sandy'') was an extremely destructive and strong Atlantic hurricane, as well as the largest Atlantic hurricane on record as measured by diameter, with tropical-storm-force winds spann ...
(2012) with a gale diameter of * The longest-lasting hurricane was the 1899 San Ciriaco hurricane, which lasted for 27 days and 18 hours as a tropical cyclone. * The longest-tracked hurricane was
Hurricane Faith Hurricane Faith was a long-lived Cape Verde hurricane and was the sixth named storm and fifth hurricane of the 1966 Atlantic hurricane season. Faith developed from an area of disturbed weather between Cape Verde and the west coast of Africa on A ...
, which traveled for as a tropical cyclone. Faith is also the northernmost moving tropical cyclone in the Atlantic basin. * The most
tornado A tornado is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, altho ...
es spawned by a hurricane was 127 by
Hurricane Ivan Hurricane Ivan was a large, long-lived, Cape Verde hurricane that caused widespread damage in the Caribbean and United States. The cyclone was the ninth named storm, the sixth hurricane and the fourth major hurricane of the active 2004 Atlan ...
( 2004 season). * The strongest landfalling
hurricane A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depend ...
was the
Labor Day Hurricane of 1935 The Great Labor Day Hurricane of 1935 was the most intense Atlantic hurricane to make landfall on record by pressure, with winds of up to 185 mph (297 km/h). The fourth tropical cyclone, third tropical storm, second hurricane, and se ...
(892 hPa). * The deadliest hurricane was the
Great Hurricane of 1780 The Great Hurricane of 1780 was the deadliest Atlantic hurricane on record. An estimated 22,000 people died throughout the Lesser Antilles when the storm passed through the islands from October 10 to October 16. Specifics on the hurricane's tr ...
(22,000 fatalities). * The deadliest hurricane to make landfall on the continental United States was the Galveston Hurricane in 1900 which may have killed up to 12,000 people. * The most damaging hurricane was both
Hurricane Katrina Hurricane Katrina was a destructive Category 5 Atlantic hurricane that caused over 1,800 fatalities and $125 billion in damage in late August 2005, especially in the city of New Orleans and the surrounding areas. It was at the time the cost ...
and
Hurricane Harvey Hurricane Harvey was a devastating Category 4 hurricane that made landfall on Texas and Louisiana in August 2017, causing catastrophic flooding and more than 100 deaths. It is tied with 2005's Hurricane Katrina as the costliest t ...
of the
2005 File:2005 Events Collage V2.png, From top left, clockwise: Hurricane Katrina in the Gulf of Mexico; the Funeral of Pope John Paul II is held in Vatican City; "Me at the zoo", the first video ever to be uploaded to YouTube; Eris was discovered in ...
and 2017 seasons, respectively, both of which caused $125 billion in damages in their respective years.Eric S. Blake, Edward N. Rappaport, and
Chris Landsea Christopher William "Chris" Landsea is an American meteorologist, formerly a research meteorologist with the Hurricane Research Division of the Atlantic Oceanographic and Meteorological Laboratory at NOAA, and now the Science and Operations Offic ...

The Dealiest, Costliest, and Most Intense United States Tropical Cyclones From 1851 to 2006 (and other frequently requested hurricane facts).
Retrieved on 2008-03-19.
However, when adjusted for inflation, Katrina is the costliest with $161 billion. *The quickest forming hurricane was Hurricane Humberto in 2007. It was a minimal hurricane that formed and intensified faster than any other tropical cyclone on record before landfall. Developing on September 12, 2007, in the northwestern Gulf of Mexico, the cyclone rapidly strengthened and struck High Island, Texas, with winds of about early on September 13.


Trends


Paleoclimatology and historical trends

Proxy records based on paleotempestological research have revealed that major hurricane activity along the
Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...
coast varies on timescales of centuries to millennia. Few major hurricanes struck the Gulf coast during 3000–1400 BC and again during the most recent millennium. These quiescent intervals were separated by a hyperactive period during 1400 BC and 1000 AD, when the Gulf coast was struck frequently by catastrophic hurricanes and their landfall probabilities increased by 3–5 times. This millennial-scale variability has been attributed to long-term shifts in the position of the
Azores High The Azores High also known as North Atlantic (Subtropical) High/Anticyclone or the Bermuda-Azores High, is a large subtropical semi-permanent centre of high atmospheric pressure typically found south of the Azores in the Atlantic Ocean, at the Hor ...
, which may also be linked to changes in the strength of the
North Atlantic Oscillation The North Atlantic Oscillation (NAO) is a weather phenomenon over the North Atlantic Ocean of fluctuations in the difference of atmospheric pressure at sea level (SLP) between the Icelandic Low and the Azores High. Through fluctuations in the ...
. According to the Azores High hypothesis, an anti-phase pattern is expected to exist between the Gulf of Mexico coast and the Atlantic coast. During the quiescent periods, a more northeasterly position of the Azores High would result in more hurricanes being steered towards the Atlantic coast. During the hyperactive period, more hurricanes were steered towards the Gulf coast as the Azores High was shifted to a more southwesterly position near the Caribbean. Such a displacement of the Azores High is consistent with paleoclimatic evidence that shows an abrupt onset of a drier climate in
Haiti Haiti (; ht, Ayiti ; French: ), officially the Republic of Haiti (); ) and formerly known as Hayti, is a country located on the island of Hispaniola in the Greater Antilles archipelago of the Caribbean Sea, east of Cuba and Jamaica, and ...
around 3200 14C years BP, and a change towards more humid conditions in the
Great Plains The Great Plains (french: Grandes Plaines), sometimes simply "the Plains", is a broad expanse of flatland in North America. It is located west of the Mississippi River and east of the Rocky Mountains, much of it covered in prairie, steppe, an ...
during the late-Holocene as more moisture was pumped up the
Mississippi Valley The Mississippi River is the List of longest rivers of the United States (by main stem), second-longest river and chief river of the second-largest Drainage system (geomorphology), drainage system in North America, second only to the Hudson B ...
through the Gulf coast. Preliminary data from the northern Atlantic coast seem to support the Azores High hypothesis. A 3,000-year proxy record from a coastal lake in
Cape Cod Cape Cod is a peninsula extending into the Atlantic Ocean from the southeastern corner of mainland Massachusetts, in the northeastern United States. Its historic, maritime character and ample beaches attract heavy tourism during the summer mont ...
suggests that hurricane activity increased significantly during the past 500–1000 years, just as the Gulf Coast was amid a quiescent period during the last millennium. Evidence also shows that the average latitude of hurricane impacts has been steadily shifting northward, towards the Eastern Seaboard over the past few centuries. This change has been sped up in modern times due to the Arctic Ocean heating up especially much from fossil fuel-caused global warming. The number and strength of Atlantic hurricanes may undergo a 50–70 year cycle, also known as the Atlantic Multidecadal Oscillation. Nyberg ''et al.'' reconstructed Atlantic major hurricane activity back to the early eighteenth century and found five periods averaging 3–5 major hurricanes per year and lasting 40–60 years, and six other averaging 1.5–2.5 major hurricanes per year and lasting 10–20 years. These periods are associated with the Atlantic multidecadal oscillation. Throughout, a decadal oscillation related to solar irradiance was responsible for enhancing/dampening the number of major hurricanes by 1–2 per year.


Climate change

Between 1979 and 2019, the intensity of tropical cyclones increased: globally, tropical cyclones are 8% more likely to reach major intensity, defined as Saffir–Simpson categories 3 to 5. This trend is particularly strong North Atlantic, where the probability of cyclones reaching category three or higher increased by 49% per decade. This is consistent with the theoretical understanding of the link between
climate change and tropical cyclones Climate change can affect tropical cyclones in a variety of ways: an intensification of rainfall and wind speed, a decrease in overall frequency, an increase in the frequency of very intense storms and a poleward extension of where the cyclones r ...
and model studies. While the number of storms in the Atlantic has increased since 1995, there is no obvious global trend. The annual number of tropical cyclones worldwide remains about 87 ± 10. However, the ability of climatologists to make long-term data analysis in certain basins is limited by the lack of reliable historical data in some basins, primarily in the Southern Hemisphere. It has been observed that a poleward migration exists for the paths of maximum intensity of tropical cyclone activity in the Atlantic. The focus of that research was on the latitude at which recent tropical cyclones in the Atlantic are reaching maximum intensity. The data indicates that during the past thirty years, the peak intensity of these storms has shifted poleward in both hemispheres at a rate of approximately 60 km per decade, amounting to approximately one degree of latitude per decade.


Impact

Atlantic storms are becoming more financially destructive, since five of the ten most expensive storms in United States history have occurred since 1990. According to the
World Meteorological Organization The World Meteorological Organization (WMO) is a specialized agency of the United Nations responsible for promoting international cooperation on atmospheric science, climatology, hydrology and geophysics. The WMO originated from the Internati ...
, "recent increase in societal impact from tropical cyclones has largely been caused by rising concentrations of population and infrastructure in coastal regions." Pielke ''et al.'' (2008) normalized mainland U.S. hurricane damage from 1900–2005 to 2005 values and found no remaining trend of increasing absolute damage. The 1970s and 1980s were notable because of the extremely low amounts of damage compared to other decades. The decade 1996–2005 has the second most damage among the past 11 decades, with only the decade 1926–1935 surpassing its costs. The most damaging single storm is the
1926 Miami hurricane The Great Miami Hurricane of 1926 was a large and intense tropical cyclone that devastated the Greater Miami area and caused catastrophic damage in the Bahamas and the U.S. Gulf Coast in September of the year 1926, accruing a US$100 mill ...
, with $157 billion of normalized damage. Often in part because of the threat of hurricanes, many coastal regions had sparse population between major ports until the advent of automobile tourism; therefore, the most severe portions of hurricanes striking the coast may have gone unmeasured in some instances. The combined effects of ship destruction and remote landfall severely limit the number of intense hurricanes in the official record before the era of hurricane reconnaissance aircraft and satellite meteorology. Although the record shows a distinct increase in the number and strength of intense hurricanes, therefore, experts regard the early data as suspect.
Christopher Landsea Christopher William "Chris" Landsea is an American meteorologist, formerly a research meteorologist with the Hurricane Research Division of the Atlantic Oceanographic and Meteorological Laboratory at NOAA, and now the Science and Operations Offi ...
''et al.'' estimated an undercount bias of zero to six tropical cyclones per year between 1851 and 1885 and zero to four per year between 1886 and 1910. These undercounts roughly take into account the typical size of tropical cyclones, the density of shipping tracks over the Atlantic basin, and the amount of populated coastline. Although more uncommon since 1995, few above-normal hurricane seasons occurred during 1970–94. Destructive hurricanes struck frequently from 1926 to 1960, including many major New England hurricanes. Twenty-one Atlantic tropical storms formed in
1933 Events January * January 11 – Sir Charles Kingsford Smith makes the first commercial flight between Australia and New Zealand. * January 17 – The United States Congress votes in favour of Philippines independence, against the wis ...
, a record only recently exceeded in
2005 File:2005 Events Collage V2.png, From top left, clockwise: Hurricane Katrina in the Gulf of Mexico; the Funeral of Pope John Paul II is held in Vatican City; "Me at the zoo", the first video ever to be uploaded to YouTube; Eris was discovered in ...
and
2020 2020 was heavily defined by the COVID-19 pandemic, which led to global Social impact of the COVID-19 pandemic, social and Economic impact of the COVID-19 pandemic, economic disruption, mass cancellations and postponements of events, COVID- ...
, which saw 28 and 30 storms, respectively. Tropical hurricanes occurred infrequently during the seasons of 1900–25; however, many intense storms formed during 1870–99. During the 1887 season, 19 tropical storms formed, of which a record 4 occurred after November 1 and 11 strengthened into hurricanes. Few hurricanes occurred in the 1840s to 1860s; however, many struck in the early 19th century, including an 1821 storm that made a direct hit on New York City. Some historical weather experts say these storms may have been as high as Category 4 in strength. These active hurricane seasons predated satellite coverage of the Atlantic basin. Before the satellite era began in 1960, tropical storms or hurricanes went undetected unless a reconnaissance aircraft encountered one, a ship reported a voyage through the storm, or a storm landed in a populated area. The official record, therefore, could miss storms in which no ship experienced gale-force winds, recognized it as a tropical storm (as opposed to a high-latitude extra-tropical cyclone, a tropical wave, or a brief squall), returned to port, and reported the experience.


See also

* Atlantic hurricane season * Atlantic hurricane seasons * Hebert Box *
Lists of Atlantic hurricanes Lists of Atlantic hurricanes, or tropical cyclones in the Atlantic Ocean, are organized by the properties of the hurricane or by the location most affected. By property * List of Atlantic hurricane seasons *List of Atlantic hurricane records *Li ...
*
List of historical tropical cyclone names Tropical cyclones are named for historical reasons and so as to avoid confusion when communicating with the public, as more than one tropical cyclone can exist at a time. Names are drawn in order from predetermined lists. They are usually assign ...
*
List of United States hurricanes The list of United States hurricanes includes all tropical cyclones officially recorded to have produced sustained winds of greater than in the United States, which is the minimum threshold for hurricane intensity. The list, which is sorted by U ...
*
Mediterranean tropical cyclone Mediterranean tropical-like cyclones, often referred to as medicanes (a portmanteau of Mediterranean hurricanes) but sometimes also as Mediterranean cyclones or as Mediterranean hurricanes, are meteorological phenomena occasionally observed over ...
*
Pacific hurricane A Pacific hurricane is a mature tropical cyclone that develops within the northeastern and central Pacific Ocean to the east of 180°W, north of the equator. For tropical cyclone warning purposes, the northern Pacific is divided into three regio ...
*
South Atlantic tropical cyclone South Atlantic tropical cyclones are unusual weather events that occur in the Southern Hemisphere. Strong wind shear, which disrupts the formation of cyclones, as well as a lack of weather disturbances favorable for development in the South Atl ...
*
Western Hemisphere Warm Pool The Western Hemisphere Warm Pool (WHWP) is a region of sea surface temperatures (SST) warmer than 28.5 °C that develops west of Central America in the spring, then expands to the Tropics, tropical waters to the east. The WHWP includes the tr ...


Notes


References


External links


Current map of mean sea level air pressures in the North AtlanticNational Hurricane Center
{{Authority control Atlantic hurricanes *