ABSTRACT
South Florida has a tropical climate, with a summer wet season and a dry season from mid fall through late spring. Average temperatures are warm all year, with only occasional freezes associated with winter cold fronts. Thunderstorms are the major source of rainfall, although erratically occurring tropical cyclones and winter frontal systems can contribute significantly in some years. Besides the annual cycle, rainfall patterns are associated with a minor bimodal peak during the wet season and a 5-to 6-year cycle associated with global climate cycles. The long-term trend in total annual precipitation has been essentially constant over the past 100 years. Evapotranspiration is lowest during the cool winter months and highest in late spring, after which it declines only slightly during the summer months. Freezes play a large role in controlling the distribution of tropical elements of the fauna and flora of south Florida. In general, they are more severe farther north or inland from the ocean. There is no clear evidence of any change in frequency or severity of freezes over the last 40 years. Droughts can significantly alter composition and structure of aquatic animal communities, provide opportunities for germination of wetland vegetation, and set the stage for fire. Individual droughts may affect all of south Florida, but they are frequently restricted only to portions of it. Tropical cyclones
© St. Lucie Press CCC 0-9634030-2-8 1/94/$ 100/$.50 225
are major late summer/early fall storms that can severely affect coastal areas. However, they have relatively minor long-term effects on biota of the more interior portions of south Florida. The erratic distribution in space and time of these climatic disturbance events contributes to the maintenance of the structural and biological diversity of the overall Everglades landscape.
