Vandalia Weather in September

What's the weather like in Vandalia (Illinois) in September 2025?

The climate in Vandalia during September can be summarized as warm, humid and a little damp.

September is in the fall / autumn in Vandalia and is typically the 4th warmest month of the year. Daytime maximum temperatures average around 27°C (80°F), whilst at night 14°C (56°F) is normal.

Vandalia weather averages (imperial / metric)
Daytime temperature 26.5°C 79.7°F
Nightly temperature 13.5°C 56.3°F
Average temperature 20°C 68°F
Daily sunshine 8.8 hrs
Avg rainfall 87 mm 3.4 ins
Rainy days 8 days
Sea temperature 21.3°C 70.4°F
Humidity 72%
Windspeed 13.3kph 8 mph

On average September is the 6th wettest month of the year in Vandalia with around 87mm 3.4 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 8.8 hours of sunshine per day.

September temperatures in Vandalia

Vandalia average temperature in September

September rainfall

Vandalia average rain in September

September hourly sunshine

Vandalia 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 Vandalia 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

Vandalia weather stats

Vandalia weather statistics
Hottest month: July 30.9°C 87.6°F
Driest month: January 48mm 1.9ins
Sunniest month: July 11hrs
Coldest month: January 2.2°C 36°F
Wettest month: April 102mm 4ins
Map showing location of Vandalia (38.9606, -89.09368) Vandalia map pin © Google

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