The highest day temperature in September 2025 was 96°F. The lowest night temperature was 76°F. The average values for day and night temperatures during September were 90.8°F и 79.7°F respectivly.

The average sea surface temperature in September 2025 for Siesta Key was 88.7°F. The maximum and minimum values were 87.0°F and 90.8°F respectively.

Most of the days in September are cloudy but you can also expect sunny or gloomy days.

Precipitation total in September for Siesta Key is 2.2 in. It makes september one of the most rainy months of the year.

The average wind speed in September is 8.1 mph. This value is relatively stable throughout the year.

We are using day length and cloud cover information for each day of the month to calculate averages for this chart. Average sunny hours for Siesta Key in September is 6.6 hours.