<P> The climate of South Florida is located across the broad transition zone between subtropical and tropical climates (Koppen Cfa and Aw). Like most regions with this climate type, there are two basic seasons--a "dry season" (winter) which runs from November through April, and a "wet season" (summer) which runs from May through October . About 70% of the annual rainfall in south Florida occurs in the wet season--often as brief but intense tropical downpours . The dry season sees little rainfall and dew points and humidity are often quite low . The dry season can be severe at times, as wildfires and water restrictions are often in place . </P> <P> The annual range of temperatures in south Florida and the Everglades is rather small (less than 20 ° F (11 ° C))--ranging from a monthly mean temperature of around 65 ° F (18 ° C) in January to 83 ° F (28 ° C) in July . High temperatures in the hot and wet season (summer) typically exceed 90 ° F (32 ° C) across inland south Florida (although coastal locations are cooled by winds from the Gulf of Mexico and the Atlantic Ocean), while high temperatures in the dry winter season average from 70 to 79 ° F (21 to 26 ° C). Frost and freeze is rare across south Florida and the Everglades; annually coastal cities like Miami and Naples report zero days with frost, although a few times each decade low temperatures may fall between 30 and 40 ° F (− 1 and 4 ° C) across South Florida . Annual rainfall averages approximately 62 inches (160 cm), with the Eastern Coastal Ridge receiving the majority of precipitation and the area surrounding Lake Okeechobee receiving about 48 inches (120 cm). </P> <P> Unlike any other wetland system on earth, the Everglades are sustained primarily by the atmosphere . Evapotranspiration--the sum of evaporation and plant transpiration from the Earth's land surface to atmosphere--associated with thunderstorms, is the key mechanism by which water leaves the region . During a year unaffected by drought, the rate may reach 40 inches (100 cm) a year . When droughts take place, the rate may peak at over 50 inches (130 cm), and exceed the amount of rainfall . As water leaves an area through evaporation from groundwater or from plant matter, activated primarily by solar energy, it is then moved by wind patterns to other areas that border or flow into the Everglades watershed system . Evapotranspiration is responsible for approximately 70--90 percent of water entering undeveloped wetland regions in the Everglades . </P> <P> Precipitation during the wet season is primarily caused by air mass thunderstorms and the easterly flow out of the subtropical high (Bermuda High). Intense daytime heating of the ground causes the warm moist tropical air to rise, creating the afternoon thundershowers typical of tropical climates. 2: 00 pm is the mean time of daily thundershowers across South Florida and the Everglades . Late in the wet season (August and September), precipitation levels reach their highest levels as tropical depressions and lows add to daily rainfall . Occasionally, tropical lows can become severe tropical cyclones and cause significant damage when the make landfall across south Florida . Tropical storms average one a year, and major hurricanes about once every ten years . Between 1871 and 1981, 138 tropical cyclones struck directly over or close to the Everglades . Strong winds from these storms disperse plant seeds and replenish mangrove forests, coral reefs, and other ecosystems . Dramatic fluctuations in precipitation are characteristic of the South Florida climate . Droughts, floods, and tropical cyclones are part of the natural water system in the Everglades . </P>

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