Fairfield Weather in September

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

The climate in Fairfield during September can be summarized as warm, humid and reasonably dry.

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

Fairfield weather averages (imperial / metric)
Daytime temperature 26.9°C 80.3°F
Nightly temperature 13.6°C 56.4°F
Average temperature 20.2°C 68.4°F
Daily sunshine 8.8 hrs
Avg rainfall 78 mm 3.1 ins
Rainy days 8 days
Sea temperature 21.6°C 70.9°F
Humidity 72%
Windspeed 12.2kph 8 mph

On average September is the 5th driest month of the year in Fairfield with around 78mm 3.1 inches of rain making it a reasonably dry 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 Fairfield

Fairfield average temperature in September

September rainfall

Fairfield average rain in September

September hourly sunshine

Fairfield 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 Fairfield 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

Fairfield weather stats

Fairfield weather statistics
Hottest month: July 31°C 87.8°F
Driest month: January 66mm 2.6ins
Sunniest month: July 11hrs
Coldest month: January 2.7°C 36.9°F
Wettest month: May 112mm 4.4ins
Map showing location of Fairfield (38.37894, -88.35977) Fairfield map pin © Google

Locations nearby

Top United States locations