San Francisco, California weather in September

Averages from 2021–2025 (150 days of record).

Average high: 69°F
Average low: 58°F
Rainy days: ~2 per month
Total precipitation: 0.2 in
Warmest recorded: 100°F
Coldest recorded: 52°F

Expect September days in San Francisco, California to top out around 69°F and cool to about 58°F overnight, with roughly 2 days of measurable rain across the month. In recent years September has ranged from 52°F to 100°F.

Other months

January February March April May June July August October November December

Current San Francisco, California forecast → · Historical data by Open-Meteo (ERA5).