St. Louis
September
Weather in St. Louis for September 2025
Your guide to St. Louis weather in September - trends and predictions
In general, the average temperature in St. Louis at the beginning of September is 31.1 °F. As the month progressed, temperatures tended to significantly cool down, reaching an average of 27.1 °F by the end of September.
St. Louis sees moderate rainfall in September, averaging 8 rainy days.
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22
Dry days
8
Rainy days
0
Snow days
31°/16°
Temperatures
15 km/h
Avg max wind
57 %
Avg humidity
St. Louis in September average weather
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| Mon. | Tue. | Wed. | Thu. | Fri. | Sat. | Sun. |
|---|---|---|---|---|---|---|
| 1  32° | 2  31° | 3 32° | 4  32° | 5  33° | 6 31° | 7  27° |
| 8  27° | 9 30° | 10 33° | 11 33° | 12  27° | 13 27° | 14 29° |
| 15 30° | 16 30° | 17 28° | 18 30° | 19 32° | 20 30° | 21  29° |
| 22 31° | 23 25° | 24 24° | 25 27° | 26 29° | 27  26° | 28 27° |
| 29 28° | 30 29° |
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Temperatures trend during September in St. Louis
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 | Sunny | 32° /15° | 0 mm | 8 | |
| Sept. 2 | Mist | 31° /14° | 0 mm | 8 | |
| Sept. 3 | Mist | 32° /17° | 0 mm | 7 | |
| Sept. 4 | Patchy rain possible | 32° /18° | 0.2 mm | 8 | |
| Sept. 5 | Thundery outbreaks possible | 33° /20° | 0 mm | 8 | |
| Sept. 6 | Patchy rain possible | 31° /19° | 1.1 mm | 7 | |
| Sept. 7 | Partly cloudy | 27° /13° | 0 mm | 7 | |
| Sept. 8 | Overcast | 27° /11° | 0 mm | 7 | |
| Sept. 9 | Mist | 30° /12° | 0 mm | 7 | |
| Sept. 10 | Sunny | 33° /14° | 0 mm | 8 | |
| Sept. 11 | Overcast | 33° /18° | 0 mm | 8 | |
| Sept. 12 | Heavy rain | 27° /17° | 12.2 mm | 7 | |
| Sept. 13 | Sunny | 27° /14° | 2.8 mm | 7 | |
| Sept. 14 | Sunny | 29° /14° | 0 mm | 7 | |
| Sept. 15 | Partly cloudy | 30° /15° | 0.1 mm | 7 | |
| Sept. 16 | Overcast | 30° /17° | 0.2 mm | 7 | |
| Sept. 17 | Overcast | 28° /16° | 0 mm | 6 | |
| Sept. 18 | Mist | 30° /14° | 0 mm | 7 | |
| Sept. 19 | Sunny | 32° /15° | 0 mm | 8 | |
| Sept. 20 | Overcast | 30° /17° | 3.2 mm | 7 | |
| Sept. 21 | Moderate or heavy rain shower | 29° /18° | 30.9 mm | 7 | |
| Sept. 22 | Patchy rain possible | 31° /18° | 38.6 mm | 7 | |
| Sept. 23 | Overcast | 25° /17° | 15.1 mm | 6 | |
| Sept. 24 | Patchy rain possible | 24° /17° | 8.3 mm | 6 | |
| Sept. 25 | Mist | 27° /14° | 0.6 mm | 6 | |
| Sept. 26 | Thundery outbreaks possible | 29° /15° | 0 mm | 7 | |
| Sept. 27 | Patchy light rain with thunder | 26° /17° | 1.8 mm | 6 | |
| Sept. 28 | Fog | 27° /17° | 2.6 mm | 6 | |
| Sept. 29 | Partly cloudy | 28° /17° | 0 mm | 7 | |
| Sept. 30 | Sunny | 29° /17° | 0 mm | 7 | |
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Important Notice
Our weather forecast for St. Louis 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 St. Louis forecast closer to your planned date for the most up-to-date weather information.
St. Louis in September - FAQ
What are the expected maximum and minimum temperatures in St. Louis during September?
Expect warm days with temperatures around 31°, cooling to mild conditions of 16° after sunset. Perfect for those who enjoy warm weather.
How much rainfall should be expected in St. Louis during September?
Moderate rainfall is anticipated in St. Louis during September, with a total of 76.2 mm spread over approximately 8 days. Considering plans for rainy days is advisable.
What are the typical wind conditions in St. Louis during September?
The average wind speed in St. Louis during September is 15 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in St. Louis
Explore the daily rainfall trends and prepare for St. Louiss September weather 💧
UV exposure in St. Louis during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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