What is the weather like in Chicago vs St. Louis in September?

In September, Chicago averages 25°C high / 17°C low with about 63 mm of rain; St. Louis averages 29°C high / 15°C low with about 83 mm.

Chicago vs St. Louis in September

Chicago is the better pick in September — 91 vs 85 on SeasonMap's comfort score. Chicago is warm, a little rain, clean air, while St. Louis is hot, rainy, clean air.

Chicago vs St. Louis — September climate, side by side

	Chicago	St. Louis
Comfort score	91/100 (S)	85/100 (A)
Feels-like high	25°C	30°C
Avg high / low	25° / 17°	29° / 15°
Rainfall	63 mm	83 mm
Rainy days	7	5
Humidity	73%	67%
Air quality (AQI)	45	50

Monthly climate normals (ERA5 reanalysis). Comfort scores are SeasonMap estimates.

Chicago vs St. Louis in September — FAQ

Is September better in Chicago or St. Louis?: Chicago is the better pick in September — 91 vs 85 on SeasonMap's comfort score. Chicago is warm, a little rain, clean air, while St. Louis is hot, rainy, clean air.
What is the weather like in Chicago vs St. Louis in September?: In September, Chicago averages 25°C high / 17°C low with about 63 mm of rain; St. Louis averages 29°C high / 15°C low with about 83 mm.