San Francisco weather in September: San Francisco, California: normal highs, lows, rain and records for September
San Francisco in September has a normal high of 70°F and a normal low of 56°F, a daily mean of 63°F, holding near 70°F all month. Measurable precipitation falls on 1 days in a normal September, 0.10 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 21°C and low of 13°C, 3 mm of precipitation in September.
- NOAA stationSan Francisco Downtown
- Station IDUSW00023272
- Location37.77°N 122.43°W
- Elevation150 ft (46 m)
- Population827,526
- Jan 58° 47°
- Feb 60° 48°
- Mar 62° 49°
- Apr 63° 50°
- May 64° 51°
- Jun 67° 53°
- Jul 66° 54°
- Aug 68° 56°
- Sep 70° 56°
- Oct 70° 54°
- Nov 64° 51°
- Dec 58° 47°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is San Francisco in September?
The normal high is 70°F and the normal low 56°F, for a daily mean of 62.9°F. September is 1.2°F warmer than August and 0.8°F warmer than October. September is the warmest month of the year in San Francisco and the 10th wettest. Across the month the normal high rises 1°F, from 70°F on September 1 to 71°F on September 30. From one year to the next September's mean temperature typically moves about 2.2°F either way (NOAA's standard deviation), so roughly two Septembers in three average between 61°F and 65°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 7%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| September 1 | 70°F | 56°F | 3% | 1% |
| September 8 | 70°F | 56°F | 3% | 1% |
| September 15 | 70°F | 56°F | 4% | 1% |
| September 22 | 71°F | 56°F | 5% | 2% |
| September 30 | 71°F | 55°F | 7% | 3% |
Every day of September: normal high, low and chance of precipitation (warmest afternoon September 25, coldest night September 29)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| September 1 | 70°F | 56°F | 3% | 1% | 13 h |
| September 2 | 70°F | 56°F | 3% | 1% | 13 h |
| September 3 | 70°F | 56°F | 3% | 1% | 13 h |
| September 4 | 70°F | 56°F | 3% | 1% | 13 h |
| September 5 | 70°F | 56°F | 3% | 1% | 12 h 50 min |
| September 6 | 70°F | 56°F | 3% | 1% | 12 h 50 min |
| September 7 | 70°F | 56°F | 3% | 1% | 12 h 50 min |
| September 8 | 70°F | 56°F | 3% | 1% | 12 h 50 min |
| September 9 | 70°F | 56°F | 4% | 1% | 12 h 40 min |
| September 10 | 70°F | 56°F | 4% | 1% | 12 h 40 min |
| September 11 | 70°F | 56°F | 4% | 1% | 12 h 40 min |
| September 12 | 70°F | 56°F | 4% | 1% | 12 h 40 min |
| September 13 | 70°F | 56°F | 4% | 1% | 12 h 30 min |
| September 14 | 70°F | 56°F | 4% | 1% | 12 h 30 min |
| September 15 | 70°F | 56°F | 4% | 1% | 12 h 30 min |
| September 16 | 70°F | 56°F | 5% | 1% | 12 h 30 min |
| September 17 | 70°F | 56°F | 5% | 1% | 12 h 20 min |
| September 18 | 70°F | 56°F | 5% | 2% | 12 h 20 min |
| September 19 | 70°F | 56°F | 5% | 2% | 12 h 20 min |
| September 20 | 70°F | 56°F | 5% | 2% | 12 h 20 min |
| September 21 | 71°F | 56°F | 5% | 2% | 12 h 10 min |
| September 22 | 71°F | 56°F | 5% | 2% | 12 h 10 min |
| September 23 | 71°F | 56°F | 6% | 2% | 12 h 10 min |
| September 24 | 71°F | 56°F | 6% | 2% | 12 h 10 min |
| September 25 | 71°F | 56°F | 6% | 2% | 12 h 10 min |
| September 26 | 71°F | 56°F | 6% | 2% | 12 h |
| September 27 | 71°F | 56°F | 6% | 2% | 12 h |
| September 28 | 71°F | 56°F | 6% | 3% | 12 h |
| September 29 | 71°F | 55°F | 7% | 3% | 12 h |
| September 30 | 71°F | 55°F | 7% | 3% | 11 h 50 min |
- Normal high
- 70°FSeptember average
- Normal low
- 56°FSeptember average
- Precipitation
- 0.10 inmonth total
- Days with precipitation
- 10.01 inch or more
- Days at 90°F or more
- 1
- Daylight
- 13 h to 11 h 50 minSeptember 1 to September 30
- Days at 70°F or more
- 14
- Days at 80°F or more
- 5
- Sunshine
- 82%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00023272; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in San Francisco in September?
On a given September day the chance of 0.01 inch or more is 4% on average, highest around September 30 (7%). In all, 0.10 in falls on 1 days of a normal September.
In a normal September in San Francisco, 1 days reach 90°F.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00023272.
What are the records for September in San Francisco?
The warmest September temperature on this station's record (since 1874) is 106°F, on September 1, 2017; the coldest is 47°F, on September 30, 1900. The wettest September brought 5.07 in (1904).
The September mean against the 1991-2020 normal of 62.9°F: 2021 62.0°F (−0.9), 2022 65.2°F (+2.3), 2023 62.8°F (−0.1), 2024 62.3°F (−0.6), 2025 65.0°F (+2.1), 2026 63.8°F (+0.9). 3 of 6 ran warmer than normal.
| September | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 62.0°F | −0.9°F | 0.07 in |
| 2022 | 65.2°F | +2.3°F | 0.34 in |
| 2023 | 62.8°F | −0.1°F | 0.11 in |
| 2024 | 62.3°F | −0.6°F | 0.00 in |
| 2025 | 65.0°F | +2.1°F | 0.11 in |
| 2026 | 63.8°F | +0.9°F | 0.03 in |
Source: records: ACIS, station USW00023272; recent months: ACIS, station USW00023272. Records and recent months use complete months only.
How does September in San Francisco compare across California?
Across the 219 places PlainClimate covers in California, September normal highs run from 64°F in Eureka to 104°F in Brawley; San Francisco's is 70°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.
Other months and places
- San Francisco in August68°F by day, 56°F at night
- San Francisco in October70°F by day, 54°F at night
- San Francisco through the yearEvery month, frost dates, records and recent years
- California in SeptemberThe statewide normal and the warmest and coolest places
- Brawley: California's warmest Septembernormal high 104°F