What is the weather like in Chicago vs San Francisco in September?

In September, Chicago averages 25°C high / 17°C low with about 63 mm of rain; San Francisco averages 22°C high / 14°C low with about 3 mm.

Chicago vs San Francisco in September

San Francisco is the better pick in September — 96 vs 91 on SeasonMap's comfort score. San Francisco is nice, dry, clean air, while Chicago is warm, a little rain, clean air.

Chicago vs San Francisco — September climate, side by side

	Chicago	San Francisco
Comfort score	91/100 (S)	96/100 (S)
Feels-like high	25°C	21°C
Avg high / low	25° / 17°	22° / 14°
Rainfall	63 mm	3 mm
Rainy days	7	1
Humidity	73%	75%
Air quality (AQI)	45	35

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

Chicago vs San Francisco in September — FAQ

Is September better in Chicago or San Francisco?: San Francisco is the better pick in September — 96 vs 91 on SeasonMap's comfort score. San Francisco is nice, dry, clean air, while Chicago is warm, a little rain, clean air.
What is the weather like in Chicago vs San Francisco in September?: In September, Chicago averages 25°C high / 17°C low with about 63 mm of rain; San Francisco averages 22°C high / 14°C low with about 3 mm.