The highest day temperature in September 2025 was 92°F. The lowest night temperature was 83°F. The average values for day and night temperatures during September were 88.8°F и 86.0°F respectivly.

The average sea surface temperature in September 2025 for Islamorada was 90.8°F. The maximum and minimum values were 89.6°F and 92.8°F respectively.

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

Precipitation total in September for Islamorada is 2.1 in. It makes september the most rainy month of the year.

The average wind speed in September is 9.8 mph. It makes September the most windless month of the year for Islamorada.

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 Islamorada in September is 6.5 hours.