The highest day temperature in September 2025 was 95°F. The lowest night temperature was 77°F. The average values for day and night temperatures during September were 90.6°F и 82.2°F respectivly.

The average sea surface temperature in September 2025 for Sanibel Island was 89.6°F. The maximum and minimum values were 87.6°F and 91.8°F respectively.

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

Precipitation total in September for Sanibel Island is 2.0 in. It makes september one of the most rainy months of the year.

The average wind speed in September is 7.9 mph. It makes September one of the most windless months of the year for Sanibel Island.

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 Sanibel Island in September is 6.5 hours.