The highest day temperature in September 2025 was 96°F. The lowest night temperature was 70°F. The average values for day and night temperatures during September were 87.7°F и 74.7°F respectivly.

The average sea surface temperature in September 2025 for Charleston was 82.0°F. The maximum and minimum values were 78.2°F and 85.0°F respectively.

You can expect various weather conditions during September. Be ready for sunny, cloudy or even gloomy days.

Precipitation total in September for Charleston is 4.3 in. It makes september one of the most rainy months of the year.

The average wind speed in September is 8.3 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 Charleston in September is 7.3 hours.