Union Weather in September

What's the weather like in Union (Missouri) in September 2025?

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

September is in the fall / autumn in Union 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 (58°F) is normal.

Union weather averages (imperial / metric)
Daytime temperature 26.5°C 79.6°F
Nightly temperature 14.2°C 57.5°F
Average temperature 20.3°C 68.5°F
Daily sunshine 8.4 hrs
Avg rainfall 88 mm 3.4 ins
Rainy days 8 days
Sea temperature 21.2°C 70.1°F
Humidity 72%
Windspeed 14.4kph 9 mph

On average September is the 5th wettest month of the year in Union with around 88mm 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 8.4 hours of sunshine per day.

September temperatures in Union

Union average temperature in September

September rainfall

Union average rain in September

September hourly sunshine

Union 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 Union 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

Union weather stats

Union weather statistics
Hottest month: July 31.4°C 88.5°F
Driest month: January 45mm 1.8ins
Sunniest month: July 10.8hrs
Coldest month: January 3.2°C 37.8°F
Wettest month: May 111mm 4.4ins
Map showing location of Union (38.45005, -91.00848) Union map pin © Google

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