Chicago Weather in September

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

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

September is in the fall / autumn in Chicago and is typically the 4th warmest month of the year. Daytime maximum temperatures average around 24°C (75°F), whilst at night 12°C (54°F) is normal.

Chicago weather averages (imperial / metric)
Daytime temperature 23.6°C 74.5°F
Nightly temperature 12.4°C 54.3°F
Average temperature 18°C 64.4°F
Daily sunshine 8.2 hrs
Avg rainfall 87 mm 3.4 ins
Rainy days 9 days
Sea temperature 19.7°C 67.5°F
Humidity 72%
Windspeed 15.1kph 9 mph

On average September is the 5th wettest month of the year in Chicago with around 87mm 3.4 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 8.2 hours of sunshine per day.

September temperatures in Chicago

Chicago average temperature in September

September rainfall

Chicago average rain in September

September hourly sunshine

Chicago 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 Chicago 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

Chicago weather stats

Chicago weather statistics
Hottest month: July 28.3°C 82.9°F
Driest month: February 38mm 1.5ins
Sunniest month: July 11hrs
Coldest month: January -1.4°C 29.5°F
Wettest month: July 100mm 3.9ins
Map showing location of Chicago (41.85003, -87.65005) Chicago map pin © Google

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