Humid subtropical climate
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.
[5] Other areas have a more uniform or varying rainfall cycles but consistently lack any predictably dry summer months unlike Mediterranean climates (which lie at similar latitudes but, in most continents, on opposite coasts).
Most summer rainfall occurs during thunderstorms that build up due to the intense surface heating and strong subtropical sun angle.
Winter rainfall (and occasional snowfall, especially near the poleward margins) is often associated with large storms in the westerlies that have fronts that reach down into subtropical latitudes.
The influence of the strong Siberian anticyclone in East Asia brings colder winter temperatures than in the humid subtropical zones in South America, and Australia.
The 0 °C (32 °F) isotherm reaches as far south as the valleys of the Yellow and Wei rivers, roughly latitude 34° N. At Hainan Island and in Taiwan, the climate transitions from subtropical into tropical.
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.
However, the humid subtropical climates exhibited here typically differ markedly from those in East Asia (and, for that matter, a good portion of the globe).
Summers tend to be relatively longer and very hot, starting from mid-April and peaking in June, extending up to July with high temperatures often exceeding 40 °C (104 °F).
Summers usually begin dry, complete with dust storms, traits typically associated with arid or semi-arid climates, before eventually transforming into a more humid July.
Closely resembling the climate patterns of neighboring Northern Indian plains, this region shows a distinct three season pattern- relatively dry and very hot summer (March- early June), extremely wet, cooler Monsoon season (June- September), and mild, foggy winter (Late October- February).
Southeast Asian locations with these climates can feature cool temperatures, with lows reaching 10 °C (50 °F) during the months of December, January, and February.
Unlike a good portion of East Asian locations with this climate however, most of Southeast Asia seldom experiences snowfall.
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.
Temperatures range from 22 °C (72 °F) in summer to 5 °C (41 °F) in winter and rainfall is even heavier than in Caspian Iran, up to 2,300 millimetres (91 in) per year in Hopa (Turkey).
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.
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, Charlotte, Dallas, Memphis, Nashville, and Raleigh, snow only occasionally falls and is usually three inches or less.
[18][20][21][22] Precipitation is plentiful in North America's humid subtropical climate zone – 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 – such as in Jacksonville, Charleston, Mobile, New Orleans, and Virginia Beach.
A semblance of a monsoon pattern (dry winters/wet summers) is evident along the Atlantic coast from the Chesapeake Bay region and the Outer Banks south to Florida.
The climate extends over a few states of southern Brazil, including Paraná, into sections of Paraguay, all of Uruguay and central Argentina (Pampas region).
[27] 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 40 °C (104 °F) are not uncommon.
The most intense 2-3 day rainfall periods that occur in this coastal zone however are the outcome of east coast lows forming to the north of a large high pressure system.
Due to climate change, some cities on the Balkan peninsula and in the Pannonian Basin such as Belgrade, Novi Sad, Niš and Budapest are now just warm enough to be categorized as such.
At 48°N, the urban core of Vienna, in Austria and Bratislava, in Slovakia, lie on the northern limit of the humid subtropical zone.
The cities include Trieste, Venice, and Rimini in Italy, Rijeka and Split in Croatia, Koper in Slovenia and Kotor in Montenegro.
Along the Black Sea coast of Bulgaria (Varna), coast of Romania (Constanța and Mamaia), Sochi, Russia and Crimea, have summers too warm (>22 °C (72 °F) mean temperature 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 due to colder winters.
