Typical September weather
St. Louis
Missouri · September
81° days
61° nights
about 5 rainy days · 12½ hours of daylight
What to pack
- Sunscreen
What September feels like
The Great Forest Park Balloon Race and the Balloon Glow the night before draw enormous, cheerful crowds mid-month. Mornings finally turn comfortable, though a late run of heat is still entirely possible and locals do not pack the shorts away yet.
Expect about 5 days with real rain — enough to notice, not enough to plan around. Humidity stays comfortable; the air never feels heavy. about 5 afternoons top 90°.
The numbers
| Typical high | 81° |
|---|---|
| Typical low | 61° |
| Days with real rain | 5 |
| Total rain | 3.0 in |
| Humidity | comfortable |
| Sunrise / sunset (mid-month) | 6:42 am / 7:09 pm |