St. Louis (MO)
September
Weather in St. Louis, Missouri for September 2026
Your guide to St. Louis weather in September - trends and predictions
Until now, September 2026 in St. Louis has been significantly warmer than historical averages.
The forecast for the next days in St. Louis predicts temperatures to be around 31 °F, close to the historical average.
In general, the average temperature in St. Louis at the beginning of September is 30.9 °F. As the month progressed, temperatures tended to noticeably cool down, reaching an average of 28.6 °F by the end of September.
The climate of St. Louis in September is notably wet, with an average of 15 rainy days, and a total of 156.3 mm of precipitation.
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Temperatures
Rain 🌧️
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15
Dry days
15
Rainy days
0
Snow days
29°/17°
Temperatures
16 km/h
Avg max wind
60 %
Avg humidity
St. Louis Weather September
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Temperatures trend during September in St. Louis
See the weather trend as well as the moving average line
September weather in St. Louis day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Sunny | 32° /17° | 0.6 mm | 7 | |
| Sept. 2 | Sunny | 32° /17° | 0.1 mm | 7 | |
| Sept. 3 |  Overcast | 31° /19° | 2.4 mm | 7 | |
| Sept. 4 |  Moderate or heavy rain shower | 31° /19° | 9.8 mm | 7 | |
| Sept. 5 | Overcast | 30° /19° | 0.8 mm | 7 | |
| Sept. 6 |  Patchy rain possible | 30° /18° | 6.4 mm | 7 | |
| Sept. 7 | Sunny | 30° /15° | 0.2 mm | 7 | |
| Sept. 8 | Sunny | 29° /13° | 0.1 mm | 7 | |
| Sept. 9 | Sunny | 29° /14° | 0.4 mm | 7 | |
| Sept. 10 | Sunny | 30° /15° | 8.4 mm | 6 | |
| Sept. 11 |  Light drizzle | 29° /22° | 11.8 mm | 6 | |
| Sept. 12 | Sunny | 33° /21° | 0 mm | 7.4 | |
| Sept. 13 | Sunny | 35° /24° | 0 mm | 7.4 | |
| Sept. 14 | Sunny | 37° /23° | 0 mm | 7.4 | |
| Sept. 15 | Sunny | 39° /27° | 2.7 mm | 9 | |
| Sept. 16 | Sunny | 36° /23° | 5.9 mm | 9 | |
| Sept. 17 | Patchy rain possible | 23° /17° | 2.7 mm | 6 | |
| Sept. 18 | Sunny | 24° /13° | 0 mm | 6 | |
| Sept. 19 | Sunny | 25° /13° | 0 mm | 6 | |
| Sept. 20 | Sunny | 26° /14° | 0 mm | 7 | |
| Sept. 21 | Sunny | 27° /15° | 0 mm | 7 | |
| Sept. 22 | Overcast | 29° /18° | 0 mm | 6 | |
| Sept. 23 | Sunny | 34° /22° | 0 mm | 8 | |
| Sept. 24 | Overcast | 35° /23° | 0 mm | 9 | |
| Sept. 25 |  Fog | 26° /15° | 0.4 mm | 6 | |
| Sept. 26 | Sunny | 28° /14° | 0 mm | 7 | |
| Sept. 27 | Sunny | 28° /16° | 0.7 mm | 7 | |
| Sept. 28 | Sunny | 28° /15° | 1 mm | 7 | |
| Sept. 29 | Sunny | 28° /15° | 0 mm | 7 | |
| Sept. 30 | Sunny | 27° /16° | 0.2 mm | 6 | |
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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.
Change Month
St. Louis in September - FAQ
What are the expected maximum and minimum temperatures in St. Louis during September?
During September, expect a variety of temperatures with highs around 29° and lows near 17°, suitable for diverse activities and preferences.
How much rainfall should be expected in St. Louis during September?
Significant rainfall exceeding 156.3 mm is expected in St. Louis during September, occurring over more than 15 days. Preparing for wet conditions is recommended in your planning.
What are the typical wind conditions in St. Louis during September?
The average wind speed in St. Louis during September is 16 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 💧
Typically, St. Louis has 15 rainy days in September with a total of 156.3 mm of rainfall.
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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