A humid subtropical climate is a zone of climate characterized by hot and humid summers, and cold to mild winters. These climates normally lie on the southeast side of all continents, generally between latitude
s 25° and 40° (sometimes 45°) and are located poleward from adjacent tropical climates. It is also known as warm temperate climate.
While many subtropical climates tend to be located at or near coastal locations, in some cases, they extend inland, most notably in China
and the United States
, where they exhibit more pronounced seasonal variations and sharper contrasts between summer and winter, as part of a gradient between the more tropical climates of the southern coasts of these countries and the more continental climates of China
and the United States
' northern and central regions (localities around the Ohio and Yangtze rivers exhibiting continental influence from the north, compared to climates around the Gulf of Mexico
and the South China Sea
, which exhibit tropical influence due to their southern coastal positions).
Under the Köppen climate classification
, ''Cfa'' and ''Cwa'' climates are either described as humid subtropical climates or mild temperate climates. This climate features mean temperature in the coldest month between or and and mean temperature in the warmest month or higher. However, while some climatologists have opted to describe this climate type as a "humid subtropical climate", Köppen himself never used this term. The humid subtropical climate classification was officially created under the Trewartha Climate classification. In this classification, climates are termed humid subtropical when they have at least 8 months with a mean temperature above .
Under the Holdridge life zones
classification, the subtropical climates have a biotemperature between the frost or critical temperature line, (depending on locations in the world) and , and these climates are humid (or even perhumid or superhumid) when the potential evapotranspiration
(PET) ratio (= PET / Precipitation) is less than 1. In the Holdridge classification, the humid subtropical climates coincide more or less with the warmest ''Cfa'' and ''Cwa'' climates and the less warm humid tropical "Köppen" climates (''Aw'', ''Am'' and ''Af'').
In a humid subtropical climate, summers are typically long, hot and humid. Monthly mean summer temperatures are normally between . A deep current of tropical air dominates the humid subtropics at the time of high sun, and daily intense (but brief) convective thundershowers are common. Summer high temperatures are typically in the high 20s to mid-30s °C (80s or 90s °F), while overnight lows in the summer are typically in the lower 20s °C (70s °F). Monthly mean temperatures in winter are often mild, typically averaging . Daytime highs in winter normally are in the range, while overnight lows are from , though the poleward boundaries of this climate feature colder temperatures.
Rainfall often shows a summer peak, especially where monsoon
s are well developed, as in Southeast Asia
and South Asia
. Other areas have a more uniform or varying rainfall cycles, but consistently lack any predictably dry summer months. Most summer rainfall occurs during thunderstorms
that build up due to the intense surface heating and strong subtropical sun angle. Weak tropical low
s that move in from adjacent warm tropical oceans, as well as infrequent tropical storms often contribute to summer seasonal rainfall peaks. Winter rainfall is often associated with large storms in the westerlies
that have fronts that reach down into subtropical latitudes. However, many subtropical climates such as southeast Asia and Florida in the United States have very dry winters, with frequent brush fires and water shortages.
Breakdown of letters
''Cfa'': ''C'' = Mild temperate ''f'' = Fully humid ''a'' = Hot Summer
''Cwa'': ''C'' = Mild temperate ''w'' = Dry Winter ''a'' = Hot Summer
In Africa, humid subtropical climates are primarily found in the southern hemisphere of the continent. The ''Cwa'' climate is found over a large portion of the interior of the Middle
and Eastern African
regions. This area includes central Angola
, northeastern Zimbabwe
, the Niassa
provinces of Mozambique
, the southern Congo
provinces, southwest Tanzania
, and the majority of Malawi
, and Zambia
. Some lower portions of the Ethiopian Highlands
also have this climate.
The climate is also found in the narrow coastal sections of southern and eastern South Africa
, primarily in KwaZulu-Natal
and the Eastern Cape
provinces. South Africa's version of this climate features heavy oceanic influences resulting in generally milder temperatures. This is particularly evident in its winters when temperatures do not drop as low as in many other regions within the humid subtropical category.
and Southeast Asia
, this climate type is found in the southeastern quarter of mainland China
from Hong Kong north to Nanjing, the northern half of Taiwan
, northern Myanmar, northern Vietnam, north through southern and central Japan (Kyushu
and half of Honshu
), and the most southern regions of Korea (the south coast and Jeju island
). Cities near the equatorward boundary of this zone include Hong Kong
; while Tokyo
are near the northern boundary.
The influence of the strong Siberian anticyclone
in East Asia brings colder winter temperatures than in the humid subtropical zones in North America, South America, and Australia. The isotherm reaches as far south as the valleys of the Yellow
rivers, roughly latitude 34° N
. At Hainan Island
and in Taiwan, the climate transitions from subtropical into tropical. In most of this region, the winter monsoon is very well developed, as such eastern Asian humid subtropical zones have a strong winter dry season and heavy summer rainfall.
Only in inland areas below the Yangtze River and coastal areas between approximately the Huai River
and the beginning of the coast of Guangdong
is there sufficient winter rainfall to produce a ''Cfa'' climate; even in these areas, rainfall and streamflow
display a highly pronounced summer peak, unlike other regions of this climate type. Drought
can be severe and often catastrophic to agriculture in the ''Cwa'' zone.
The only area where winter precipitation equals or even exceeds the summer rain is around the San'in region
at the western coast of Japan, which during winter is on the windward side of the westerlies. The winter precipitation in these regions is usually produced by low-pressure systems off the east coast that develop in the onshore flow from the Siberian high. Summer rainfall comes from the East Asian Monsoon and from frequent typhoon
s. Annual rainfall is generally over , and in areas below the Himalayas can be much higher still.
Humid subtropical climates can also be found in South Asia
, primarily along the Ganges River
also in the southern part of India
which is near the equator
. Parts of hilly and Terai of Nepal
are marked subtopical. However, the humid subtropical
climates exhibited here differ markedly from those in East Asia
(and for that matter a good portion of the globe). Winters here are typically mild, dry and relatively short. They also tend to be foggy. Summers tend to be long and very hot, starting from mid-April and peaking in May and early June with high temperatures often exceeding . They also tend to be extremely dry, complete with dust storm
s, traits usually associated with arid
or semi-arid climate
s. During this period many native trees defoliate to save water. This is followed by the cooler monsoon
s, where the region experiences heavy rains on almost a daily basis. Average high temperatures decrease during the monsoon season, but humidity increases. This results in hot and humid conditions, similar to summers in other humid subtropical climates. Cities such as New Delhi
exhibit this atypical version of the climate in India. In Nepal cities such as Kathmandu
have subtropical climate. In Pakistan, the twin cities of Islamabad
, as well as the city of Swabi
in Khyber Pakhtunkhwa, feature this weather pattern. In Bangladesh
, cities like Rangpur
fetures this climatic condition.
In South Asia, humid subtropical climates generally border on continental climates as altitude increases, or on winter-rainfall climates in western areas of Pakistan and northwestern India (e.g. Peshawar
in northwestern Pakistan or Srinagar
in the Kashmir Valley
in India, where the primary precipitation peak occurs in March, not July or August). Further east, in highland areas with lengthier monsoons such as Nepal, seasonal temperature variation is lower than in the lowlands.
Although humid subtropical climates in Asia are mostly confined to the southeastern quarter of the continent, there are two narrow areas along the coast of the Caspian Sea
and Black Sea
with humid subtropical climates. Summers in these locations are cooler than typical humid subtropical climates and snowfall in winter is relatively common, but is usually of a short duration.
In Western Asia
, the climate is prevalent in the Gilan
and Māzandarān Province
s of Iran
, in parts of the Caucasus
, in Azerbaijan
and in Georgia
wedged between the Caspian
seas and coastal (Black Sea
) Turkey, albeit having more oceanic influence.
Annual rainfall ranges from around at Sari
to over at Bandar-e Anzali
, and is heavy throughout the year, with a maximum in October or November when Bandar-e Anzali can average 400 millimetres (16 inches). Temperatures are generally moderate in comparison with other parts of Western Asia. During winter, the coastal areas can receive snowfall, which is usually of a short duration.
, the average maximum in July is around but with near-saturation humidity
, whilst in January it is around . The heavy, evenly distributed rainfall extends north into the Caspian coastal strip of Azerbaijan
up to its northern border but this climate in Azerbaijan is, however, a ''Cfb''/''Cfa'' (''Oceanic climate''/''Humid subtropical climate'') borderline case.
) in the Kolkheti Lowland
and the northeast coast of Turkey
), have a climate similar to that of Gilan and Mazandaran in Iran and very similar to that of southeastern and northern Azerbaijan. Temperatures range from in summer to in winter and rainfall is even heavier than in Caspian Iran, up to per year in Hopa
(Turkey). These climates are a ''Cfb''/''Cfa'' (''Oceanic climate''/''Humid subtropical climate'') borderline case.
In North America, humid subtropical climates are found in the American Gulf and lower East Coast states, including Texas
, North Carolina
, South Carolina
, and Florida
. On the Florida peninsula, the humid subtropical climate gives way to the tropical climate
of South Florida
and the Florida Keys
Under Köppen's climate classification, the climate can also be found in the Mid-Atlantic, primarily eastern Virginia
, the lower elevations of West Virginia
, Washington, D.C.
, New Jersey
, southeastern Pennsylvania
and far southern New York
, specifically New York City
and sections of Long Island
. It can also be found in the Midwest, primarily in the central and southern portions of Kansas and Missouri, and the southern portions of Illinois, Indiana and Ohio.
, there are small areas of ''Cfa'' and ''Cwa'' climates. The climate can be found in small areas scattered around the northeastern part of the country, in proximity to the Gulf of Mexico
. Other areas where the climate can be found is in the high elevations of Trans-Mexican Volcanic Belt and Sierra Madre Oriental. Despite being located at higher elevations, these locations have summers that are too warm to qualify as a subtropical highland climate. Guadalajara
's climate is a major example of this.
Outside of isolated sections of Mexico, the southernmost limits of this climate zone in North America
lie just north of South Florida and around southern coastal Texas. Cities at the southernmost limits, such as Tampa and Orlando and along the Texas coast around Corpus Christi
down toward Brownsville
generally feature warm weather year-round and minimal temperature differences between seasons. In contrast, cities at the northernmost limits of the climate zone such as New York, Philadelphia and Louisville
feature hot, humid summers and chilly winters. These areas have average winter temperatures at the coldest limit of climates classed as humid subtropical.
varies greatly in this climate zone. In locations at the southern limits of this zone and areas around the Gulf Coast
, cities such as Orlando, Tampa, Houston, New Orleans, and Savannah rarely see snowfall, which occurs, at most, a few times per generation. In Southern cities farther north or inland, such as Atlanta
, Oklahoma City
, and Raleigh
, snow only occasionally falls and is usually three inches or less. However, for the majority of the winter here, temperatures remain above or well above freezing.
At the northernmost limits of this zone, cities such as New York City, Philadelphia
, and Baltimore
typically see snowfall during the winter, with occasional heavy snowstorms. Still, average temperatures during a typical winter hover just above freezing at these locations.
Precipitation is plentiful in the humid subtropical climate zone in North America – but with significant variations in terms of wettest/driest months and seasons. Much of the interior South, including Tennessee, Kentucky, and the northern halves of Mississippi and Alabama, tends to have a winter or spring (not summer) precipitation maximum. Closer to the South Atlantic
and Gulf coasts, there is a summer maximum, with July or August usually the wettest month – as at Norfolk, Cape Hatteras and Jacksonville, North Carolina, Charleston, South Carolina, Mobile, Alabama and New Orleans. A semblance of a monsoon pattern (dry winters/wet summers) is evident along the Atlantic coast from southern North Carolina (Wilmington, North Carolina area) south to Florida. The seasonal monsoon is much stronger on the Florida peninsula, as most locations in Florida have dry winters and wet summers.
In addition, areas in Texas that are slightly inland from the Gulf of Mexico, such as Austin and San Antonio that border the semi-arid climate
zone, generally see a peak of precipitation in May, a drought-like nadir in mid-summer and a secondary, if not equal, precipitation peak in September or October. Areas further south along South Texas
' Gulf Coast (Brownsville), which closely border tropical climate classification
, typically have a strong September precipitation maximum, and a tendency toward dry conditions in winter with rain increasing in spring, with December or January often the driest months.
Humid subtropical climates are found in a sizable portion of South America. The climate extends over a few states of southern Brazil, including Paraná
, into sections of Paraguay
, all of Uruguay
, and the Río de la Plata
region in Argentina. Major cities such as São Paulo
, Buenos Aires
, Porto Alegre
, have a humid subtropical climate, generally in the form of hot and humid summers, and mild to cool winters. These areas, which include the Pampas
, generally feature a ''Cfa'' climate categorization. At 38°S
, the Argentine city of Bahía Blanca
lies on the southern limit of the humid subtropical zone.
The ''Cwa'' climate occurs in parts of tropical highlands of São Paulo state
, Mato Grosso do Sul
and near the Andean highland
in northwestern Argentina
. These highland areas feature summer temperatures that are warm enough to fall outside the subtropical highland climate
The humid subtropical climate zone predominantly lies in eastern Australia, which begins from the coastal strip of Mackay, Queensland
and stretches down to the southern coast of Sydney
, where it transitions into the cooler, oceanic climates.
, approximately northeast of Sydney, the ''Cfa'' zone would extend to inland New South Wales
, excluding the highland regions (which have an oceanic climate), stretching towards Dubbo
to the northwest and Wagga Wagga
to the south, ending at the New South Wales/Victoria
To note, these places would have characteristics of the semi-arid and/or Mediterranean climates. Furthermore, the inland ''Cfa'' climates generally have drier summers, or at least summers with low humidity.
Extreme heat is more often experienced in Sydney than in other large cities in Australia's ''Cfa'' zone, especially in the western suburbs
, where highs over are not uncommon. Frost is prevalent in the more inland areas of Sydney, such as Richmond
. Average annual rainfall in the Sydney region ranges between .
There is usually a distinct summer rainfall maximum that becomes more pronounced moving northwards. In Brisbane, the wettest month (February) receives five times the rainfall of the driest month (September). Temperatures are very warm to hot but are not excessive: the average maximum in February is usually around and in July around . Frosts are extremely rare except at higher elevations, but temperatures over are not common on the coast.
North of the ''Cfa'' climate zone there is a zone centred upon Rockhampton
which extends north to the Köppen ''Cwa'' classified climate zone of the Atherton Tablelands region. This region has a very pronounced dry winter period, with often negligible rainfall between June and October. Winter temperatures generally only fall slightly below , which would classify the region as a tropical savanna, or ''Aw'', climate.
Annual rainfall within Australia's humid subtropical climate zone can reach as high as in coastal locations and is generally or above. The most intense 2-3 day rainfall periods that occur in this coastal zone however are the outcome of east coast low
s forming to the north of a large high pressure system
, there can be great variation in rainfall amounts from year to year as a result of these systems. As an example Lismore
which lies in the centre of this zone, the annual rainfall can range from less than in 1915 to more than in 1950.
The Po Valley
, in Northern Italy
, including major cities such as Milan
, and Verona
, has a humid subtropical climate, featuring hot, humid summers with frequent thunderstorms; winters are foggy, damp and chilly, with sudden bursts of frost. Some parts of the valley have a mild continental climate. Places along the shores of Lake Maggiore
, Lake Lugano
, Lake Como
) have a humid subtropical climate with a distinctive high amount of rainfall during summer. Budapest, Hungary is just warm enough to qualify, due to recent warming. At 47°N
, the city lies on the northern limit of the humid subtropical zone.
The coastal areas in the northern half of the Adriatic Sea
also fall within this climate zone. The cities include Trieste
, and Rimini
. Other Southern European areas in the ''Cfa'' zone include the central valleys and coast of Catalonia
, some on the north-east of Spain (Huesca
), West Macedonia
), the Garonne Valley
) and Rhone Valley
) in France
Along the Black Sea
coast of Bulgaria
), coast of Romania
), Sochi, Russia
, have summers too warm (> in the warmest month) to qualify as oceanic, no freezing month, and enough summer precipitation and sometimes humid conditions, where they would be fit to be classed under ''Cfa'', though they closely border the humid continental
zone. All these areas are subject to occasional, in some cases repeated snowfalls and freezes during winter.
In Central Europe
, a small area of humid subtropical climates are located in transitional areas between the oceanic and continental climates in areas where higher summer temperature do not quite qualify it for inclusion in the Oceanic climate schema (but, in the Trewartha climate classification
, this type of climate is included in that typical of the other areas of central-west Europe, classified as Do -the Temperate Oceanic climate-) and mild winters do not allow their inclusion into continental climates. Average summer temperatures in areas of Europe
with this climate are generally not as hot as most other subtropical zones around the world.
In the Azores
, some islands have this climate, with very mild and rainy winters (>) and no snowfall, warm summers (>) but with no dry season during the warmest period, which means that they can neither be classified as oceanic
, nor as Mediterranean
, only as humid subtropical, as with Corvo Island
In many other climate classification systems outside of the Köppen, most of these locations would not be included in the humid subtropical grouping. The higher summer precipitation and poleward flow of tropical air-masses in summer are not present in Europe as they are in eastern Australia or the southern United States.
Category:Köppen climate types