Weather in San Francisco, California for September 2026
Small Craft Advisory - See hour by hour.
Until now, September 2026 in San Francisco is slightly cooler than the historical average by 1 °F.
Expect cooler weather in the next days in San Francisco with the forecast suggesting a temperature of 18.4 °F, lower than the historical average.
In general, the average temperature in San Francisco at the beginning of September is 21.4 °F. As the month progressed, temperatures tended to noticeably cool down, reaching an average of 19.3 °F by the end of September.
Precipitation in San Francisco during September is a rare event, with an average of fewer than 2 rainy days.
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San Francisco Weather September
Temperatures trend during September in San Francisco
September weather in San Francisco day by day
| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Patchy rain possible | 20° /12° | 0.7 mm | 4 | |
| Sept. 2 |  Sunny | 19° /13° | 0 mm | 6 | |
| Sept. 3 | Sunny | 22° /13° | 1.8 mm | 5 | |
| Sept. 4 | Sunny | 22° /13° | 0.1 mm | 6 | |
| Sept. 5 | Sunny | 23° /14° | 0 mm | 7 | |
| Sept. 6 | Sunny | 22° /13° | 0 mm | 6 | |
| Sept. 7 | Sunny | 22° /13° | 0 mm | 6 | |
| Sept. 8 | Sunny | 23° /13° | 0 mm | 6 | |
| Sept. 9 | Sunny | 23° /14° | 0 mm | 5 | |
| Sept. 10 |  Partly cloudy | 19° /13° | 0 mm | 5 | |
| Sept. 11 | Sunny | 18° /14° | 0 mm | 7.6 | |
| Sept. 12 | Sunny | 17° /15° | 0 mm | 8.1 | |
| Sept. 13 | Sunny | 18° /14° | 0 mm | 7.3 | |
| Sept. 14 | Sunny | 18° /15° | 0 mm | 6.9 | |
| Sept. 15 | Sunny | 19° /14° | 0 mm | 5 | |
| Sept. 16 | Sunny | 17° /15° | 0 mm | 5 | |
| Sept. 17 | Sunny | 18° /15° | 0 mm | 5 | |
| Sept. 18 | Sunny | 18° /16° | 0 mm | 5 | |
| Sept. 19 | Sunny | 17° /15° | 0 mm | 5 | |
| Sept. 20 | Sunny | 17° /14° | 0 mm | 5 | |
| Sept. 21 | Sunny | 23° /16° | 0 mm | 6 | |
| Sept. 22 | Sunny | 22° /16° | 0 mm | 6 | |
| Sept. 23 | Sunny | 18° /15° | 0 mm | 5 | |
| Sept. 24 | Sunny | 18° /14° | 0 mm | 5 | |
| Sept. 25 | Sunny | 19° /12° | 0 mm | 4 | |
| Sept. 26 | Partly cloudy | 19° /13° | 0 mm | 5 | |
| Sept. 27 |  Fog | 19° /12° | 0 mm | 5 | |
| Sept. 28 | Mist | 19° /12° | 0 mm | 5 | |
| Sept. 29 | Partly cloudy | 19° /12° | 0 mm | 5 | |
| Sept. 30 | Sunny | 22° /13° | 0.4 mm | 5 | |
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San Francisco in September - FAQ
What are the expected maximum and minimum temperatures in San Francisco during September?
How much rainfall should be expected in San Francisco during September?
What are the typical wind conditions in San Francisco during September?
September rainfall patterns in San Francisco
UV exposure in San Francisco during September
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