Climate of Puerto Rico
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The climate of Puerto Rico in the
Köppen climate classification The Köppen climate classification is one of the most widely used climate classification systems. It was first published by German-Russian climatologist Wladimir Köppen (1846–1940) in 1884, with several later modifications by Köppen, notabl ...
is predominantly
tropical rainforest Tropical rainforests are rainforests that occur in areas of tropical rainforest climate in which there is no dry season – all months have an average precipitation of at least 60 mm – and may also be referred to as ''lowland equa ...
. Temperatures throughout the year are warm to hot, averaging near in lower elevations and in the mountains. Easterly
trade wind The trade winds or easterlies are the permanent east-to-west prevailing winds that flow in the Earth's equatorial region. The trade winds blow mainly from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisph ...
s pass across the island year round while the rainy season stretches from April into November. The relatively cool trade winds are blocked by the mountains of the Cordillera Central which causes rain shadows and sharp variations in the temperature and wind speed over short distances. About a quarter of the average annual rainfall for Puerto Rico occurs during
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. Depen ...
s, which are more frequent during
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 ...
years.


Temperature

Temperatures range from in the lower elevations, while higher elevations in the central part of the island experience temperatures between year round. The temperature in the south is a few degrees higher than the north. Between winter and summer, there is only a temperature swing of around . Coastal water temperatures average between in February to in August. The highest temperature ever recorded was at San Lorenzo, while the lowest temperature ever recorded was at Aibonito. Frost and freezes have occurred in the highest mountains at almost twice the elevation of Aibonito, where the low temperature in winter is in the low 40s (5C). The average temperature in San Juan is over 80°F (27C). It is the only location in plant hardiness zone 13b on the USDA map, with temperatures rarely falling to the low 60s.


Temperature records


Climate data


Dust from the Sahara

For years, meteorologists have been studying dust that arrives from the
Sahara Desert , photo = Sahara real color.jpg , photo_caption = The Sahara taken by Apollo 17 astronauts, 1972 , map = , map_image = , location = , country = , country1 = , ...
, and they believe the dust which is carried over the Atlantic to Puerto Rico causes a whole series of changes in Puerto Rico's climate and environment, from haze to heat.


Wind

Persistent trade winds move from east to west across the island year round. When the trades winds are lighter,
sea breeze A sea breeze or onshore breeze is any wind that blows from a large body of water toward or onto a landmass; it develops due to differences in air pressure created by the differing heat capacities of water and dry land. As such, sea breezes ar ...
and land breeze circulations dominate. Every five years or so a
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 ...
brings high intensity wind.Alexa J. Andrews
Spatial and Temporal Variability of Tropical Storm and Hurricane Strikes in the Bahamas, and the Greater and Lesser Antilles.
Retrieved on 2007-01-23.
The island's infrastructure is extremely susceptible to high winds. For example, when Hurricane Maria made landfall on the island in 2017 at Category 5 strength, 100% of the power grid was lost.


Rainfall

There is a pronounced rainy season from April to November and a dry season from December to March, causing some drought. Due to the island's topography, rainfall varies greatly across the island. Pico del Este averages of rainfall yearly while Magueyes Island averages only a year.


Severe weather

* Puerto Rico experiences the Atlantic
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 ...
season, similar to the remainder of the Caribbean Sea and North Atlantic oceans. On average, a quarter of its annual rainfall is contributed by tropical cyclones, which is more prevalent during periods of La Niña than
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 ...
. A cyclone of tropical storm strength passes near Puerto Rico, on average, every five years. A hurricane passes in the vicinity of the island, on average, every 11 years. Two Category 5 hurricanes have struck the island since 1851: the Lake Okeechobee Hurricane of September 1928, and
Hurricane Irma Hurricane Irma was an extremely powerful Cape Verde hurricane that caused widespread destruction across its path in September 2017. Irma was the first Category 5 hurricane to strike the Leeward Islands on record, followed by Maria two ...
of September 2017. * Sometimes
waterspout A waterspout is an intense columnar vortex (usually appearing as a funnel-shaped cloud) that occurs over a body of water. Some are connected to a cumulus congestus cloud, some to a cumuliform cloud and some to a cumulonimbus cloud. In the ...
s form off the coast during showers and thunderstorms, particularly off the west coast, with tornadoes and hailstorms possible in the inner sea. These thunderstorms may be formed due to tropical waves,
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. Depen ...
s, and frontal boundaries which become stationary across the region between fall and spring. * In September 2017, Puerto Rico was hit by Category 5
Hurricane Irma Hurricane Irma was an extremely powerful Cape Verde hurricane that caused widespread destruction across its path in September 2017. Irma was the first Category 5 hurricane to strike the Leeward Islands on record, followed by Maria two ...
, which had maximum sustained winds of 290 km/h (180 mph). It was and still is the strongest hurricane to hit the island in recorded history. While the eye itself stayed offshore (passing about 60 miles from land), the eye-wall skirted the island's northeastern portion, including the population centre of San Juan. Nearly 70% of the island lost power from the hurricane. The power and infrastructure grid were severely weakened by this storm, leading to more damage from
Hurricane Maria Hurricane Maria was a deadly Category 5 hurricane that devastated the northeastern Caribbean in September 2017, particularly Dominica, Saint Croix, and Puerto Rico. It is regarded as the worst natural disaster in recorded history to affect ...
, two weeks later. *
Hurricane Maria Hurricane Maria was a deadly Category 5 hurricane that devastated the northeastern Caribbean in September 2017, particularly Dominica, Saint Croix, and Puerto Rico. It is regarded as the worst natural disaster in recorded history to affect ...
made landfall on Puerto Rico on Wednesday, September 20, near the Yabucoa municipality at 10:15 UTC (6:15am local time) as a high-end Category 4 hurricane with winds of . In addition, heavy rainfall occurred throughout the territory, peaking at in
Caguas Caguas (, ) is a city and municipality of Puerto Rico located in the Central Mountain Range of Puerto Rico, south of San Juan and Trujillo Alto, west of Gurabo and San Lorenzo, and east of Aguas Buenas, Cidra, and Cayey. Caguas was founde ...
. The
eyewall replacement cycle In meteorology, eyewall replacement cycles, also called concentric eyewall cycles, naturally occur in intense tropical cyclones, generally with winds greater than , or major hurricanes ( Category 3 or above). When tropical cyclones reach this int ...
that caused María to weaken to Category 4 strength also caused the eye to triple in size as the diameter expanded prior to landfall. This change in size caused the area exposed to high-intensity winds on the island to be far greater. Widespread flooding affected San Juan, waist-deep in some areas, and numerous structures lost their roof. Approximately 80 percent of the territory's agriculture was lost due to the hurricane, with agricultural losses estimated at $780 million. The hurricane completely destroyed the island's power grid, leaving all 3.4 million residents without electricity. Hurricane Maria caused a humanitarian crisis in Puerto Rico, with damages estimated in 90 billion dollars and a loss of human life close to three thousand.


Weather by season

The Wet Season begins in April and lasts to November. The weather is hot and humid with thunderstorms in the afternoon, especially in August and September. Trade winds bring cool summer breezes in the north and east of Puerto Rico, but due to the topography of the island, these winds do not reach the coast south and west, causing much higher temperatures than in the north. During humid summer days, the heat index can reach 115 °F (47 °C) and actual temperatures can reach 100 °F (38 °C). Sometimes the wind shifts from the south, causing an inverse pattern, where the heat south of the island moves to the north, causing temperatures in the mid 90s (35 °C) in San Juan and low humidity. June is usually the driest month of the summer. During June and July the precipitation is mostly caused by the effects of humidity and heat of the island. The peak of the hurricane season comes in September. Weather conditions can be very rainy as tropical lows pass near the island, with frequent strong thunderstorms. By early November the tropical cyclone season fades and the weather becomes drier and generally sunny. December brings the Dry Season which lasts through March. Weakening cool fronts from the north lower temperatures and humidity, and dry and sunny conditions prevail. In San Juan in the winter months, high temperatures reach 77–87 °F (25–30 °C) with an average high of 83 °F and lows down to 66–76 °F (19–24 °C), giving an average of 71 °F (22 °C). In the central area of the island the elevation and reduced sea effects bring the minimum temperatures to 55–65 °F (13–18 °C) on average. After fronts pass the temperature may drop to the 40s (4–9 °C) in the mountains, in the 50s (10–15 °C) in the valleys, and in the low 60s (16 °C to 20 °C) in the coastal zone. In general the climate in the dry season is sunny, with little change from day to day. February and March are often quite dry, sunny and hot.


Sun

The sunrise varies from 5:30 a.m. in summer and 7:00 a.m. in winter. Sunset varies between 5:40 p.m. in winter and 7:10 p.m. in summer. Puerto Rico does not use daylight saving time. The ultraviolet index or UV index varies from 10+ in the summer and a maximum of 7 in winter.


See also

* Climate change in Puerto Rico * List of wettest known tropical cyclones in Puerto Rico


Notes


References


External links


Major hurricanes that have impacted on Puerto Rico

National Weather Service of San Juan, Puerto Rico

Earth Trends Climate and Atmosphere Profile
{{Portal bar, Puerto Rico, Weather
Puerto Rico Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and unincorporated ...
Geography of Puerto Rico