Weather in St Louis in September 2025
Average weather
Average temperature in St Louis in September
Going from a maximum of +93°F during the day to a minimum of +54°F during the night, the temperature in September averages around +84°F.
The average maximum temperature goes up 9% by the end of the month, compared with the beginning of the month, from +86°F to +90°F.
Is St Louis warm or cold in September?
St Louis is typically warm in September.
Maximum temperatures go down compared to the previous month from +88°F to +81°F. The minimum temperature also goes down from +68°F to +61°F.
It’s generally warm, but pack a long-sleeve shirt for evenings.
Take a look at how September is compared to other months in St Louis:
Climate in St Louis in September
| August | September | October | ||||
|---|---|---|---|---|---|---|
| Avg. temperature | ||||||
| +88°F | +81°F | +68°F | ||||
| Min. temperature | ||||||
| +48°F | +36°F | +25°F | ||||
| Max. temperature | ||||||
| +104°F | +100°F | +93°F | ||||
| Rainfall | ||||||
| 88 mm | 81 mm | 89 mm | ||||
| Wind | ||||||
| 2 m/s | 2 m/s | 2 m/s | ||||
| Humidity | ||||||
| 71% | 70% | 69% | ||||
| Air pressure | ||||||
| 1015 HPa | 1016 HPa | 1017 HPa | ||||
| Sunny days | ||||||
| 10 | 12 | 11 | ||||
| Cloudy days | ||||||
| 6 | 6 | 7 | ||||
| Rainy days | ||||||
| 14 | 12 | 12 | ||||
| Snowy days | ||||||
| 0 | 0 | 0 | ||||
September weather is still as good as in August. It’s getting colder in September. From +88°F in the day, the average maximum temperature lowers to +81°F. As September arrives, the amount of rainfall goes down. On average, the rainfall volume decreases from 88 mm to 81 mm. It feels drier, as humidity decreases from 71% to 70%. The average wind speed doesn’t change much during September, staying around 2 m/s. The good news is there are likely to be more sunny days in September, from 10 to 12.
October brings much the same weather, it remains good.
Wind
The average wind speed is 2 m/s getting up to 3 m/s which is a light breeze; barely moving the tree leaves.
The average wind speed in St Louis is gradually increasing during September, going from 1 m/s to 2 m/s over the course of the month.
Rain
How was the weather last September in St Louis?
Climate Change Over the Years
The climate in St Louis in September has not changed that much over the last 43 years.
The average temperature was the lowest in 1979 (+64°F) and the highest in 2012 (+71°F). The driest year was 2007 with only 666 mm of rainfall, and the wettest year was 2020 with 1575 mm.
FAQ
Is September a good time to visit St Louis?
Can you sunbathe in St Louis in September?
Is St Louis rainy in September?
Is it sunny in St Louis in September?
Other cities in USA
Monthly weather in St Louis
Source of the data
For this page, we’ve looked at the typical weather in St Louis, based on historical hourly weather data from January 1, 1979, to December 31, 2023.
For past dates, we show actual recorded data at the location at that time. Forecasts are based on recorded weather during that day of the year, averaged over the total years for which we have records (unless stated otherwise). The daily temperature is the highest recorded temperature in the shadow during that day.