San Francisco, CA climate: monthly averages and frost dates
San Francisco, CA has mild winters and mild summers by this site's scale, with semi-arid annual precipitation. The figures are the 1991–2020 climate normals for NOAA station USW00023234 (SAN FRANCISCO INTL AP), 37 mi (60 km) in a straight line from the city's center point (US Census).
- Warmest month high
- 74.8°F
- September
- Coldest month mean
- 51.3°F
- January
- Precipitation
- 19.6 in
- per year
- Snowfall
- no data
- per year
- 32°F nights
- 0.2
- per year
Monthly averages in San Francisco
| Month | High °F | Low °F | Mean °F | Precip. in | Snow in | Days ≥0.01 in | Days ≥90°F | Nights ≤32°F |
|---|---|---|---|---|---|---|---|---|
| January | 58.0 | 44.5 | 51.3 | 3.89 | – | 10.9 | 0.0 | 0.0 |
| February | 60.8 | 46.1 | 53.5 | 3.96 | – | 10.8 | 0.0 | 0.0 |
| March | 63.4 | 47.6 | 55.5 | 2.73 | – | 10.3 | 0.0 | 0.0 |
| April | 65.6 | 49.1 | 57.3 | 1.36 | – | 6.2 | 0.1 | 0.0 |
| May | 68.3 | 51.6 | 59.9 | 0.48 | – | 3.3 | 0.4 | 0.0 |
| June | 71.5 | 53.6 | 62.5 | 0.14 | – | 1.2 | 0.7 | 0.0 |
| July | 72.6 | 55.3 | 64.0 | 0.00 | – | 0.0 | 0.3 | 0.0 |
| August | 73.4 | 56.4 | 64.9 | 0.04 | – | 0.4 | 0.6 | 0.0 |
| September | 74.8 | 55.9 | 65.3 | 0.07 | – | 0.9 | 1.6 | 0.0 |
| October | 72.3 | 53.4 | 62.9 | 0.79 | – | 3.1 | 0.5 | 0.0 |
| November | 64.3 | 48.5 | 56.4 | 2.04 | – | 7.2 | 0.0 | 0.0 |
| December | 58.2 | 44.6 | 51.4 | 4.14 | – | 11.1 | 0.0 | 0.1 |
| Year | 66.9 | 50.6 | 58.7 | 19.64 | – | 65.4 | 4.2 | 0.2 |
How cold is winter in San Francisco?
Winters in San Francisco are mild by this site's scale (coldest-month mean 45 to under 60°F). The coldest month is January, with a mean temperature of 51.3°F (10.7°C), a normal daily high of 58.0°F (14.4°C) and a normal daily low of 44.5°F (6.9°C).
The station averages 0.2 nights a year at or below 32°F.
How hot is summer in San Francisco?
Summers in San Francisco are mild by this site's scale (hottest-month high 70 to under 80°F). September has the highest normal daily high, 74.8°F (23.8°C), with nights averaging 55.9°F (13.3°C).
The high reaches 90°F or more on 4.2 days in a normal year.
What is the wettest month in San Francisco?
San Francisco gets 19.64 in (499 mm) of precipitation in a normal year, which this site classes as semi-arid (10 to under 20 in a year). The wettest month is December with 4.14 in (105 mm); the driest is July with less than 0.005 in, which NOAA rounds to 0.00.
Measurable precipitation (0.01 in or more) falls on 65.4 days a year.
Does it snow in San Francisco?
NOAA publishes no snowfall normal for station USW00023234, so this page gives no snow figures for San Francisco.
Which months are mild in San Francisco?
7 months in San Francisco meet this site's comfort thresholds (normal high 65–85°F, low 45°F or higher, fewer than 10 days with 0.10 in or more of precipitation): April to October.
November misses by one threshold only (normal high 64.3°F, below the 65°F limit).
Thresholds and their limits: methodology.
Frost dates and growing season in San Francisco
In most years no night at this station gets down to 32°F, so NOAA's median freeze-free season in San Francisco is the full year. A few years do have such nights: over 1991–2020 they average 0.2 a year.
NOAA still publishes 32°F dates from the years that do freeze, but the median spring date (December 29) and the median autumn date (December 26) cross, so they do not describe a frost season and this page does not show them as one.
The month with the highest chance of at least one 32°F night is December, at 8%.
| Threshold | Median last date (spring) | Median first date (autumn or winter) | Median season, days |
|---|---|---|---|
| 36°F | January 8 | December 24 | 353 |
| 32°F | No such night in most years, though a few years have one; no typical season to show | ||
| 28°F | No such night in a typical year (NOAA publishes no dates) | ||
| 24°F | No such night in a typical year (NOAA publishes no dates) | ||
| 20°F | No such night in a typical year (NOAA publishes no dates) | ||
| 16°F | No such night in a typical year (NOAA publishes no dates) | ||
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 4% | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 8% |
Nearby and similar places
Of the places on this site, the closest to San Francisco by station distance are Los Angeles, CA at 338 mi (544 km), Las Vegas, NV at 412 mi (663 km) and San Diego, CA at 447 mi (719 km).
Among places whose winter, summer and precipitation words are each within one band of San Francisco's (winter: mild, summer: mild, precipitation: semi-arid), the closest monthly temperature and precipitation patterns are Los Angeles, CA, San Diego, CA and Portland, OR.
Compared with Los Angeles, CA, San Francisco's peak-month normal high is 1.9°F (1.1°C) lower, its coldest-month mean is 6.3°F (3.5°C) lower, and its annual precipitation is 7.41 in more.
| Place | Listed as | Station distance | Coldest mean °F | Warmest high °F | Precip. in/yr | Snow in/yr | Last frost |
|---|---|---|---|---|---|---|---|
| San Francisco, CA | this page | – | 51.3 | 74.8 | 19.6 | – | rare freeze |
| Los Angeles, CA | nearby, similar | 338 mi (544 km) | 57.6 | 76.7 | 12.2 | – | no freeze |
| Las Vegas, NV | nearby | 412 mi (663 km) | 48.2 | 104.5 | 4.2 | 0.2 | January 20 |
| San Diego, CA | nearby, similar | 447 mi (719 km) | 57.9 | 77.3 | 9.8 | – | no freeze |
| Portland, OR | similar | 551 mi (887 km) | 41.6 | 82.3 | 36.9 | 4.2 | March 13 |
How nearby and similar places are chosen: methodology.
Source and station
The data for San Francisco come from NOAA station SAN FRANCISCO INTL AP, CA US (USW00023234) at 37.6197, -122.3647, elevation 8 ft (2 m). It lies 37 mi (60 km) in a straight line from the center point of San Francisco city, the “internal point” in the US Census 2024 Gazetteer.
Each monthly normal used here rests on at least 25 years of data from 1991–2020 (NOAA's per-field year counts).
NOAA publishes no value for 2 of the monthly fields at this station; they are shown as “no data”.
Location note: Census internal point lies offshore because the city includes the Farallon Islands; station_distance_km is not a downtown distance.
NOAA completeness flags on the monthly fields used here:
- R: Representative: meets WMO standards for data availability for 10 or more years (missing months filled from surrounding stations).
- S: Standard: meets WMO standards for data availability for 24 or more years.
Cite the data as:
Palecki, Michael; Durre, Imke; Applequist, Scott; Arguez, Anthony; Lawrimore, Jay (2021). U.S. Climate Normals 2020: U.S. Monthly Climate Normals (1991-2020). Station USW00023234 (SAN FRANCISCO INTL AP, CA US). NOAA National Centers for Environmental Information. Dataset. https://doi.org/10.25921/wck8-er13. Accessed 2026-10-09.
Palecki, Michael; Durre, Imke; Applequist, Scott; Arguez, Anthony; Lawrimore, Jay (2021). U.S. Climate Normals 2020: U.S. Annual/Seasonal Climate Normals (1991-2020). Station USW00023234 (SAN FRANCISCO INTL AP, CA US). NOAA National Centers for Environmental Information. Dataset. https://doi.org/10.25921/4ek7-fk11. Accessed 2026-10-09.
Files used: monthly normals CSV, annual/seasonal normals CSV (retrieved 2026-10-09). The values on this page as JSON: /us/ca/san-francisco/data.json.