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Missouri United States

Weather in Saint Louis County for September 2025

Your guide to Saint Louis County weather in September - trends and predictions

    Temperatures

  • In general, the average temperature in Saint Louis County at the beginning of September is 27.9 °F. As the month progressed, temperatures tended to significantly cool down, reaching an average of 22.9 °F by the end of September.

  • Rain 🌧️

  • Saint Louis County experiences moderate rainfall in September, with an average of 7 rainy days and a total precipitation of 110.8 mm.

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Average dry days
23
Dry days
Average rainy days
7
Rainy days
Average snowy days
0
Snow days
Average temperatures
27°/17°
Temperatures
Average wind speed
13 km/h
Avg max wind
Average humidity
64 %
Avg humidity

Saint Louis County Weather September

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Temperatures trend during September in Saint Louis County

See the weather trend as well as the moving average line

September weather day by day

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Date Weather Temperatures Rain UV More
Sept. 1 Fog
Fog
31° /19° 0 mm 7
Sept. 2 Sunny
Sunny
27° /16° 0 mm 7
Sept. 3 Overcast
Overcast
26° /14° 0 mm 6
Sept. 4 Sunny
Sunny
30° /14° 0 mm 8
Sept. 5 Partly cloudy
Partly cloudy
31° /17° 0 mm 8
Sept. 6 Patchy rain possible
Patchy rain possible
28° /18° 0.2 mm 6
Sept. 7 Sunny
Sunny
22° /11° 0 mm 6
Sept. 8 Sunny
Sunny
24° /8° 0 mm 6
Sept. 9 Sunny
Sunny
29° /11° 0 mm 7
Sept. 10 Sunny
Sunny
31° /13° 0 mm 8
Sept. 11 Partly cloudy
Partly cloudy
33° /17° 0 mm 8
Sept. 12 Sunny
Sunny
28° /17° 0 mm 7
Sept. 13 Patchy rain possible
Patchy rain possible
24° /17° 4.4 mm 5
Sept. 14 Mist
Mist
26° /17° 0 mm 6
Sept. 15 Light rain shower
Light rain shower
27° /18° 0.8 mm 6
Sept. 16 Partly cloudy
Partly cloudy
31° /19° 0 mm 8
Sept. 17 Cloudy
Cloudy
28° /18° 0 mm 6
Sept. 18 Sunny
Sunny
31° /17° 0 mm 8
Sept. 19 Sunny
Sunny
33° /17° 0 mm 8
Sept. 20 Moderate rain at times
Moderate rain at times
32° /22° 3.3 mm 7
Sept. 21 Thundery outbreaks possible
Thundery outbreaks possible
27° /23° 0 mm 6
Sept. 22 Moderate or heavy rain shower
Moderate or heavy rain shower
31° /21° 21.4 mm 7
Sept. 23 Moderate or heavy rain shower
Moderate or heavy rain shower
18° /16° 67.7 mm 4
Sept. 24 Moderate or heavy rain shower
Moderate or heavy rain shower
20° /18° 11.2 mm 5
Sept. 25 Fog
Fog
24° /12° 0 mm 5
Sept. 26 Fog
Fog
24° /12° 0 mm 5
Sept. 27 Overcast
Overcast
22° /18° 0 mm 5
Sept. 28 Overcast
Overcast
22° /17° 1.9 mm 5
Sept. 29 Overcast
Overcast
22° /19° 0 mm 5
Sept. 30 Mist
Mist
26° /18° 0 mm 6
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Important Notice
Our weather forecast for Saint Louis County in September is based on the analysis of historical data rather than real-time forecast models. While this provides a general overview, weather conditions can change. We recommend that you check the Saint Louis County forecast closer to your planned date for the most up-to-date weather information.

Saint Louis County in September - FAQ

What are the expected maximum and minimum temperatures in Saint Louis County during September?
During September, expect a variety of temperatures with highs around 27° and lows near 17°, suitable for diverse activities and preferences.
How much rainfall should be expected in Saint Louis County during September?
Significant rainfall exceeding 110.8 mm is expected in Saint Louis County during September, occurring over more than 7 days. Preparing for wet conditions is recommended in your planning.
What are the typical wind conditions in Saint Louis County during September?
The average wind speed in Saint Louis County during September is 13 km/h, suggesting breezy to windy conditions, depending on your activities.

September rainfall patterns in Saint Louis County

Explore the daily rainfall trends and prepare for Saint Louis Countys September weather 💧

UV exposure in Saint Louis County during September

Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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Location coordinates Where is Saint Louis County?

Get accurate weather forecasts for Saint Louis County, located at latitude 38.503 and longitude -90.628. Stay updated with localized weather information tailored for Saint Louis County.

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