San Francisco, California Climate
San Francisco weather by month — average highs and lows, rainfall, all-time records, and a 75-year warming record
San Francisco has warmed 1.4°F since 1921.
Right now it's 54° in San Francisco — about 6° below the June normal.
San Francisco weather by month
Average high and low temperature and rainfall for every month, from the 1991–2020 climate normals — the 30-year reference period meteorologists use. The taller, warmer bands are summer; the short, cool bands are winter.
San Francisco rainfall by month
San Francisco averages 22.9 inches of precipitation a year. The wettest month is December and the driest is July.
San Francisco temperature records
- All-time record high
- 106°Fset September 1, 2017
- All-time record low
- 27°Fset December 11, 1932
Records are drawn from the nearest long-term weather station’s full daily history, so they capture the most extreme single day San Francisco has recorded — not a typical seasonal high or low.
How to read San Francisco’s climate
A climate is the long-run average of weather, not any single day. The month-by-month panel above is built from San Francisco’s 1991–2020 normals — the standard 30-year window meteorologists use, long enough to average out individual hot summers and mild winters but recent enough to describe the climate you actually live in. The high–low band for each month shows the typical daily swing: a tall band means big day-to-night contrast, a short band means the air stays close to one temperature around the clock.
The warming stripes at the top tell a different story — not what a typical year looks like, but how the typical year has changed. Each stripe is one year’s average temperature, colored against the long-run mean: cool blues in the mid-20th century shading to warm reds in recent decades. That shift is the same signal behind the headline figure — San Francisco averages about 1.4°F warmer now than in 1921. The records below sit outside both averages: they’re the single most extreme days in the station’s record, the edges of what San Francisco’s weather has ever done.
Frequently asked
- What is the hottest month in San Francisco?
- In San Francisco, the hottest stretch of the year is typically July and August, when average daily high temperatures peak. The month-by-month table above shows San Francisco's exact average high and low for each month, based on the 1991–2020 climate normals — the standard 30-year reference period meteorologists use.
- What is the coldest month in San Francisco?
- San Francisco's coldest month is usually January, with December and February close behind. The averages-by-month chart above gives the exact average high and low for the coldest part of San Francisco's year, so you can see how cold a typical winter day runs.
- How much does it rain in San Francisco?
- San Francisco's total annual precipitation and its wettest and driest months are shown in the rainfall-by-month section above. Those figures are 1991–2020 normals — the average monthly precipitation total across that 30-year window — so they reflect a typical year rather than any single wet or dry season.
- What months are best to visit San Francisco?
- The most comfortable months in San Francisco are usually the shoulder seasons — spring and fall — when temperatures sit between the summer peak and winter low and rainfall is moderate. Compare the average high, low, and precipitation for each month in the table above to pick the window that fits the weather you want.
- Has San Francisco gotten hotter?
- Yes — like nearly every US city, San Francisco has warmed measurably over the long run. The warming-trend chart above plots San Francisco's annual mean temperature back to 1950 and shows the total change implied by the long-term trend line. The slope is positive, meaning recent decades average warmer than the mid-20th-century baseline.
- What is the record high temperature in San Francisco?
- San Francisco's all-time record high — the hottest single day in the archive — is shown in the records section above, along with the date it occurred. Records are drawn from the full historical window (1950 to present), so they capture the most extreme heat on record, not just a typical summer day.
- What is the record low temperature in San Francisco?
- San Francisco's all-time record low and the date it was set appear in the records section above. Like the record high, it comes from the full 1950-to-present archive, so it reflects the coldest day San Francisco has recorded rather than an average winter low.
More for San Francisco
See the full San Francisco, CA weather forecast — hour-by-hour outlook, NOAA radar, satellite, and air quality.