Weather in St. Louis, Missouri for September 2025
Meteorological - Air Quality Alert - See hour by hour.
Until now, September 2025 in St. Louis is cooler than usual, with temperatures averaging 27 °F, this is -2.3 °F below the typical seasonal average.
The forecast for the next days in St. Louis predicts temperatures to be around 29 °F, close to the historical average.
In general, the average temperature in St. Louis at the beginning of September is 29.3 °F. As the month progressed, temperatures tended to moderately fall, reaching an average of 27.9 °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 82.9 mm of precipitation.
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St. Louis Weather September
Temperatures trend during September in St. Louis
September weather in St. Louis day by day
| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Sunny | 31° /16° | 0.8 mm | 7 | |
| Sept. 2 | Sunny | 30° /16° | 0.1 mm | 7 | |
| Sept. 3 |  Overcast | 29° /17° | 2.9 mm | 7 | |
| Sept. 4 |  Moderate or heavy rain shower | 29° /18° | 11.8 mm | 7 | |
| Sept. 5 | Overcast | 28° /18° | 1 mm | 6 | |
| Sept. 6 |  Patchy rain possible | 29° /17° | 7.7 mm | 6 | |
| Sept. 7 | Sunny | 29° /15° | 0.2 mm | 7 | |
| Sept. 8 | Sunny | 28° /13° | 0.1 mm | 7 | |
| Sept. 9 | Sunny | 28° /12° | 0 mm | 7 | |
| Sept. 10 | Sunny | 30° /14° | 0.2 mm | 7 | |
| Sept. 11 |  Partly cloudy | 31° /17° | 3.2 mm | 7 | |
| Sept. 12 | Sunny | 30° /17° | 4.9 mm | 7 | |
| Sept. 13 | Sunny | 30° /16° | 1.3 mm | 7 | |
| Sept. 14 | Patchy rain possible | 37° /25° | 1.8 mm | 1.6 | |
| Sept. 15 |  Heavy rain | 34° /24° | 44.2 mm | 1.5 | |
| Sept. 16 | Partly cloudy | 32° /22° | 0 mm | 1.5 | |
| Sept. 17 | Sunny | 36° /21° | 0 mm | 1.5 | |
| Sept. 18 |  Moderate rain | 34° /20° | 8.7 mm | 0 | |
| Sept. 19 | Patchy rain possible | 31° /19° | 0.5 mm | 5 | |
| Sept. 20 | Patchy rain possible | 25° /20° | 1.7 mm | 5 | |
| Sept. 21 | Sunny | 27° /17° | 0.1 mm | 6 | |
| Sept. 22 | Patchy rain possible | 21° /17° | 4.6 mm | 4 | |
| Sept. 23 | Patchy rain possible | 20° /17° | 1.3 mm | 4 | |
| Sept. 24 | Partly cloudy | 26° /15° | 0 mm | 5 | |
| Sept. 25 | Sunny | 29° /16° | 0 mm | 6 | |
| Sept. 26 | Sunny | 30° /16° | 0 mm | 6 | |
| Sept. 27 | Sunny | 29° /16° | 0 mm | 6 | |
| Sept. 28 | Sunny | 27° /15° | 1.3 mm | 7 | |
| Sept. 29 |  Cloudy | 27° /15° | 0 mm | 7 | |
| Sept. 30 | Sunny | 27° /16° | 0.2 mm | 6 | |
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St. Louis in September - FAQ
September rainfall patterns in St. Louis
UV exposure in St. Louis during September
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