Temperature for September
In Key West, FL during September the average high temperature is 88.6°F. The hottest day on record was September 14, 1980 when the temperature hit 102.9°F.
Precipitation for September
In September the average monthly rainfall in Key West, FL is 6.17 inches with rain usually falling on between 15 and 16 days. 1983 was the driest September with only 2.49 inches of rain falling, and 1994 was the wettest September with 12.80 inches of rain. The wettest single day in September was 30 September 1994 when 5.74 inches of rain fell.
In September it usually snows on between 0 and 1 days. Tornados are reported on 1 and 2 days in September. There are thunderstorms on between 9 and 10 days in September.