South Atlantic Water Science Center - Georgia
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The Apalachicola-Chattahoochee-Flint (ACF) River National Water Quality Assessment (NAWQA) Program study
Basin Description: Climate
The ACF River basin is characterized by a warm and humid, temperate climate. Major factors influencing climate variability in the basin are latitude, altitude, and proximity to the Gulf of Mexico.
Because the ACF River basin spans about 5 degrees of latitude, it has a sharp gradient in growing seasons. Average annual temperature ranges from about 60 °F in the north to 70 °F in the south. Average daily temperatures in the basin for January range from about 40 °F to 55 °F, and for July from 75 °F to 80°F. In the winter, cold winds from the northwest cause the minimum temperature to dip below freezing for only short periods. Summer temperatures commonly range from the 70's to the 90's.
Precipitation is greatest either in the mountains as a result of their orographic effect or near the Gulf of Mexico as a result of the availability of moist air. Average annual precipitation in the basin, primarily as rainfall, is about 55 inches (in.), but ranges from a low of 45 in. in the east-central part of the basin to a high of 60 in. in the Florida panhandle (U.S. Geological Survey, 1986).
Evapotranspiration generally increases from north to south and ranges from about 32 to 42 in. per year. In the east-central part of the basin, precipitation and evapotranspiration are about equal. Average annual runoff ranges from 15 to 40 in. Runoff is greatest in the Blue Ridge Mountains and near the Gulf coast (Gebert and others, 1987).
Text extracted from Couch and others 1995.