Saint Louis Weather in September

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

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

September is in the fall / autumn in Saint Louis and is typically the 4th warmest month of the year. Daytime maximum temperatures average around a muggy 27°C (80°F), whilst at night 15°C (59°F) is normal.

Saint Louis weather averages (imperial / metric)
Daytime temperature 26.6°C 79.8°F
Nightly temperature 15.1°C 59.1°F
Average temperature 20.8°C 69.4°F
Daily sunshine 8.5 hrs
Avg rainfall 78 mm 3.1 ins
Rainy days 8 days
Sea temperature 21.2°C 70.2°F
Humidity 72%
Windspeed 14kph 9 mph

On average September is the 6th driest month of the year in Saint Louis 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 8.5 hours of sunshine per day.

September temperatures in Saint Louis

Saint Louis average temperature in September

September rainfall

Saint Louis average rain in September

September hourly sunshine

Saint Louis 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 Saint Louis 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

Saint Louis weather stats

Saint Louis weather statistics
Hottest month: July 31.4°C 88.5°F
Driest month: January 46mm 1.8ins
Sunniest month: July 10.8hrs
Coldest month: January 3.1°C 37.6°F
Wettest month: May 103mm 4.1ins
Map showing location of Saint Louis (38.62727, -90.19789) Saint Louis map pin © Google

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