San Francisco
September
Weather in San Francisco for September 2025
Your guide to San Francisco weather in September - trends and predictions
In general, the average temperature in San Francisco at the beginning of September is 21 °F. As the month progressed, temperatures tended to noticeably cool down, reaching an average of 18.1 °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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29
Dry days
1
Rainy days
0
Snow days
20°/13°
Temperatures
19 km/h
Avg max wind
82 %
Avg humidity
San Francisco in September average weather
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| Mon. | Tue. | Wed. | Thu. | Fri. | Sat. | Sun. |
|---|---|---|---|---|---|---|
| 1  19° | 2  20° | 3 23° | 4 22° | 5 22° | 6 21° | 7 20° |
| 8 21° | 9 20° | 10 19° | 11 21° | 12 20° | 13 21° | 14 20° |
| 15 18° | 16 18° | 17 17° | 18 18° | 19 14° | 20 16° | 21 17° |
| 22 17° | 23 18° | 24 17° | 25 17° | 26  18° | 27 19° | 28 17° |
| 29  18° | 30 21° |
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Temperatures trend during September in San Francisco
See the weather trend as well as the moving average line
September weather day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 | Overcast | 19° /13° | 0 mm | 4 | |
| Sept. 2 | Mist | 20° /14° | 0 mm | 5 | |
| Sept. 3 | Mist | 23° /13° | 0 mm | 6 | |
| Sept. 4 | Mist | 22° /14° | 0 mm | 6 | |
| Sept. 5 | Mist | 22° /14° | 0 mm | 6 | |
| Sept. 6 | Mist | 21° /13° | 0 mm | 6 | |
| Sept. 7 | Mist | 20° /12° | 0 mm | 6 | |
| Sept. 8 | Fog | 21° /12° | 0 mm | 6 | |
| Sept. 9 | Fog | 20° /12° | 0 mm | 5 | |
| Sept. 10 | Fog | 19° /12° | 0 mm | 5 | |
| Sept. 11 | Fog | 21° /12° | 0 mm | 6 | |
| Sept. 12 | Mist | 20° /13° | 0 mm | 5 | |
| Sept. 13 | Fog | 21° /13° | 0 mm | 6 | |
| Sept. 14 | Fog | 20° /13° | 0 mm | 5 | |
| Sept. 15 | Mist | 18° /13° | 0 mm | 5 | |
| Sept. 16 | Mist | 18° /13° | 0.3 mm | 4 | |
| Sept. 17 | Overcast | 17° /13° | 0 mm | 4 | |
| Sept. 18 | Mist | 18° /12° | 0 mm | 5 | |
| Sept. 19 | Mist | 14° /12° | 0 mm | 4 | |
| Sept. 20 | Mist | 16° /12° | 0 mm | 4 | |
| Sept. 21 | Mist | 17° /11° | 0 mm | 4 | |
| Sept. 22 | Fog | 17° /11° | 0 mm | 4 | |
| Sept. 23 | Overcast | 18° /11° | 0 mm | 4 | |
| Sept. 24 | Mist | 17° /11° | 0 mm | 5 | |
| Sept. 25 | Mist | 17° /12° | 0 mm | 4 | |
| Sept. 26 | Patchy rain possible | 18° /13° | 0.1 mm | 5 | |
| Sept. 27 | Mist | 19° /12° | 0 mm | 5 | |
| Sept. 28 | Mist | 17° /11° | 0 mm | 4 | |
| Sept. 29 | Partly cloudy | 18° /12° | 0 mm | 5 | |
| Sept. 30 | Light rain shower | 21° /13° | 0.9 mm | 5 | |
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Important Notice
Our weather forecast for San Francisco in September is based on the analysis of historical data rather than real-time forecast models. While this provides a general overview, weather conditions can change. We recommend that you check the San Francisco forecast closer to your planned date for the most up-to-date weather information.
San Francisco in September - FAQ
What are the expected maximum and minimum temperatures in San Francisco during September?
Enjoy moderate daytime temperatures of up to 20° and cooler nights around 13°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in San Francisco during September?
Rainfall in San Francisco during September is rare to nonexistent, with the total expected rainfall being less than 10 mm and approximately 1 days seeing any precipitation. Planning without the concern for rain is generally straightforward during this very dry period.
What are the typical wind conditions in San Francisco during September?
The average wind speed in San Francisco during September is 19 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in San Francisco
Explore the daily rainfall trends and prepare for San Franciscos September weather 💧
UV exposure in San Francisco during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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