Weather Forecast For September 2024 In Florida. In general, the average temperature in florida at the beginning of september is 91 °f. In september, the average heat index, which combines relative humidity and air temperature, is estimated at 105.8°f (41°c).

Get the monthly weather forecast for jacksonville, fl, including daily high/low, historical averages, to help you plan ahead. Average monthly weather with temperature, pressure, humidity, precipitation, wind, daylight, sunshine, visibility, and uv index.