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

In September, San Francisco averages 22°C high / 14°C low with about 3 mm of rain; Seattle averages 21°C high / 12°C low with about 36 mm.

San Francisco vs Seattle in September

San Francisco is the better pick in September — 96 vs 89 on SeasonMap's comfort score. San Francisco is nice, dry, clean air, while Seattle is nice, a little rain, clean air.

San Francisco vs Seattle — September climate, side by side

	San Francisco	Seattle
Comfort score	96/100 (S)	89/100 (A)
Feels-like high	21°C	21°C
Avg high / low	22° / 14°	21° / 12°
Rainfall	3 mm	36 mm
Rainy days	1	6
Humidity	75%	75%
Air quality (AQI)	35	40

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

San Francisco vs Seattle in September — FAQ

Is September better in San Francisco or Seattle?: San Francisco is the better pick in September — 96 vs 89 on SeasonMap's comfort score. San Francisco is nice, dry, clean air, while Seattle is nice, a little rain, clean air.
What is the weather like in San Francisco vs Seattle in September?: In September, San Francisco averages 22°C high / 14°C low with about 3 mm of rain; Seattle averages 21°C high / 12°C low with about 36 mm.