occurring near Sarasota Bay to the south. Average monthly temperatures 
range from 16.0°C to 27.8°C for January and August, respectively. Mean 
annual precipitation for the Tampa Bay watershed is approximately 54 
inches (Heath and Conover 1981). Based on data from 1941 to 1970, Palmer 
(1978) determined that yearly rainfall increased concentrically away from 
Tampa with the most rain falling in the eastern portions of Hillsborough 
and Manatee Counties (Figure 2). For the period 1978 to 1985, however, 
Stowers and Tabb (1987) reported a shift from this historical pattern 
with rainfall increasing in Pinellas and northwestern Hillsborough 
Counties and decreasing in the eastern portions of the watershed. The 
authors attributed this to a change in meteorological conditions 
resulting in a shift in summer winds from easterly to southwesterly but 
state that it is not known whether this represents a short-term cycle or 
a long-term displacement. What is clearly known is that the Tampa and 
Sarasota Bay area has recently been experiencing dry conditions, as 
rainfall has been below average most years since 1961. Palmer and Bone 
(1977) indicated that rainfall at 10 of 14 sites in west-central Florida 
during 1961 to 1976 was the lowest of any of 16 year period since 1915. 
More recently, major droughts occurred in west-central Florida during 
1981 and 1985. 
Figure 2. Distribution of average annual rainfall (inches) in the Tampa 
Bay region of west-central Florida, 1941-1970 (after Palmer 
1978). 
20 
