Wilmington Weather in September

What's the weather like in Wilmington (Delaware) in September 2025?

The climate in Wilmington during September can be summarized as warm and a little damp.

September is in the fall / autumn in Wilmington and is typically the 4th warmest month of the year. Daytime maximum temperatures average around 25°C (77°F), whilst at night 14°C (57°F) is normal.

Wilmington weather averages (imperial / metric)
Daytime temperature 25.2°C 77.3°F
Nightly temperature 14.1°C 57.3°F
Average temperature 19.6°C 67.3°F
Daily sunshine 7.9 hrs
Avg rainfall 97 mm 3.8 ins
Rainy days 8 days
Sea temperature 21.3°C 70.3°F
Humidity 73%
Windspeed 13.3kph 8 mph

On average September is the 4th wettest month of the year in Wilmington with around 97mm 3.8 inches of rain making it a a little damp time to visit. This rainfall is typically spread over 8 days, although this may vary considerably.

On the flip side this corresponds to an average of 7.9 hours of sunshine per day.

September temperatures in Wilmington

Wilmington average temperature in September

September rainfall

Wilmington average rain in September

September hourly sunshine

Wilmington average rain in September

The data used in these monthly averages covers a period of over 100 years right up until last year. As such they are a valid prediction of what to expect for the weather in Wilmington in September 2025.

Other monthly averages

Best places to visit in September

UV index Best time to go?

Beta

Current (hourly) weather 15 day forecast

Wilmington weather stats

Wilmington weather statistics
Hottest month: July 29.4°C 84.9°F
Driest month: February 75mm 3ins
Sunniest month: July 9.7hrs
Coldest month: January 3.3°C 37.9°F
Wettest month: July 114mm 4.5ins
Map showing location of Wilmington (39.74595, -75.54659) Wilmington map pin © Google

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