San Francisco weather in September
September is one of the best months to visit San Francisco: highs of 23°C (74°F) and about 4 mm (0.2 in) of rain on average. Nights average 12°C (54°F) and cloud cover 46% (NASA POWER, 2001–2025 averages). The sea averages 17°C (62°F). It is the 3rd driest month of the year and the warmest. Compared with August, it is warmer and wetter; October brings highs of 21°C (70°F) and 29 mm (1.1 in) of rain.
Is September a good time to visit San Francisco?
best month Weather score 90/100.
Yes. September is one of the best months for weather in San Francisco.
Does it rain a lot in San Francisco in September?
No, it is usually dry: about 4 mm (0.2 in) falls in an average September. It is the 3rd driest month of the year.
How warm is San Francisco in September?
Days average 23°C (74°F) and nights 12°C (54°F).
San Francisco weather by month
| Month | High | Low | Rain | Cloud | Sea | Weather |
|---|---|---|---|---|---|---|
| January | 13°C (55°F) | 6°C (42°F) | 100 mm | 58% | 13°C (55°F) | least pleasant |
| February | 14°C (57°F) | 7°C (44°F) | 102 mm | 58% | 13°C (55°F) | least pleasant |
| March | 15°C (60°F) | 8°C (46°F) | 82 mm | 58% | 13°C (56°F) | fair |
| April | 17°C (62°F) | 8°C (46°F) | 42 mm | 53% | 13°C (56°F) | fair |
| May | 19°C (65°F) | 9°C (49°F) | 18 mm | 51% | 13°C (56°F) | best |
| June | 21°C (70°F) | 11°C (51°F) | 6 mm | 44% | 14°C (57°F) | best |
| July | 22°C (72°F) | 12°C (53°F) | 1 mm | 56% | 15°C (59°F) | best |
| August | 23°C (73°F) | 12°C (54°F) | 1 mm | 57% | 15°C (60°F) | best |
| September | 23°C (74°F) | 12°C (54°F) | 4 mm | 46% | 17°C (62°F) | best |
| October | 21°C (70°F) | 11°C (51°F) | 29 mm | 44% | 16°C (61°F) | best |
| November | 17°C (62°F) | 8°C (47°F) | 62 mm | 50% | 14°C (57°F) | fair |
| December | 13°C (56°F) | 6°C (43°F) | 138 mm | 59% | 13°C (55°F) | least pleasant |
Sources: 2001–2025 monthly averages from NASA POWER (MERRA-2 reanalysis), sea temperature from Open-Meteo Marine. Page updated . How we rate months