Clinton Weather in September

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

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

September is in the fall / autumn in Clinton and is typically the 4th warmest month of the year. Daytime maximum temperatures average around 26°C (79°F), whilst at night 13°C (55°F) is normal.

Clinton weather averages (imperial / metric)
Daytime temperature 26.1°C 78.9°F
Nightly temperature 12.6°C 54.6°F
Average temperature 19.3°C 66.7°F
Daily sunshine 8.7 hrs
Avg rainfall 83 mm 3.3 ins
Rainy days 9 days
Sea temperature 20°C 68°F
Humidity 72%
Windspeed 14kph 9 mph

On average September is the 6th wettest month of the year in Clinton with around 83mm 3.3 inches of rain making it a a little damp time to visit. This rainfall is typically spread over 9 days, although this may vary considerably.

On the flip side this corresponds to an average of 8.7 hours of sunshine per day.

September temperatures in Clinton

Clinton average temperature in September

September rainfall

Clinton average rain in September

September hourly sunshine

Clinton 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 Clinton 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

Clinton weather stats

Clinton weather statistics
Hottest month: July 30.3°C 86.5°F
Driest month: February 46mm 1.8ins
Sunniest month: July 10.9hrs
Coldest month: January -0°C 32°F
Wettest month: July 108mm 4.3ins
Map showing location of Clinton (40.15365, -88.96453) Clinton map pin © Google

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