What is the hottest month in San Francisco?

September is San Francisco's hottest month, with the highest average daily high of the year. 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?

January is San Francisco's coldest month, with the lowest average daily low of the year. The averages-by-month chart above gives the exact average high and low for every month, 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. The warming-stripes chart above plots San Francisco's annual mean temperature for every complete year of station data from 1921 to 2022, and the trend line fitted to 1921–2022 rises about 1.4°F (+0.14°F per decade) — recent decades average warmer than the start of that window.

What is the record high temperature in San Francisco?

San Francisco's all-time record high — the hottest single day in the station record — is shown in the records section above, along with the date it occurred. Records are drawn from the nearest long-term weather station's full daily history, which begins in 1921, 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 station's full daily history back to 1921, so it reflects the coldest day on record rather than an average winter low.

San Francisco, California Climate

San Francisco weather by month — average highs and lows, rainfall, all-time records, and the warming record since 1921

Hottest month: 70°FSeptember average high
Coldest month: 47°FJanuary average low
Precipitation: 22.9 ina year
Wettest month: December4.8 in on average

1991–2020 NOAA climate normals

At 2:21 AM PDT on Sep 21 it was 53°F in San Francisco — 4° below the 57°F typical for that hour (estimated from the Sep 21 normal high of 70°F and low of 55°F, interpolated from the monthly normals).

San Francisco weather by month

Average high, low, and rainfall for every month, from San Francisco’s 1991–2020 climate normals, the standard 30-year reference period. Each band runs from the month’s average low to its average high: a tall band is a big day-to-night swing.

58°47°

4.4″Jan

60°48°

4.4″Feb

62°49°

3.1″Mar

63°50°

1.6″Apr

64°51°

0.7″May

67°53°

0.2″Jun

66°54°

0.0″Jul

68°56°

0.1″Aug

70°56°

0.1″Sep

70°54°

0.9″Oct

64°51°

2.6″Nov

58°47°

4.8″Dec

Average high → low (°F)Rainfall (inches)1991–2020 normals

San Francisco monthly weather averages — average high, average low, and rainfall for each month, from the 1991–2020 U.S. Climate Normals (NOAA).
Month	Avg High	Avg Low	Rainfall
January	58°F	47°F	4.4 in
February	60°F	48°F	4.4 in
March	62°F	49°F	3.1 in
April	63°F	50°F	1.6 in
May	64°F	51°F	0.7 in
June	67°F	53°F	0.2 in
July	66°F	54°F	0.0 in
August	68°F	56°F	0.1 in
September	70°F	56°F	0.1 in
October	70°F	54°F	0.9 in
November	64°F	51°F	2.6 in
December	58°F	47°F	4.8 in
Annual	64°F	51°F	22.9 in

San Francisco’s warming record since 1921

San Francisco has warmed 1.4°F since 1921 (+0.14°F per decade, 1921–2022 trend)

Not what a typical year looks like, but how the typical year has changed. Each stripe is one complete year’s average temperature at the station, 1921 to 2022, colored against the mean of those years: blue for cooler years, red for warmer ones. The figure under the stripes is the least-squares trend line fitted to 1921–2022 — San Francisco averages about 1.4°F warmer by that trend than in 1921.

Compared with the national rankingThe fastest-warming cities ranking fits every city to the same years, 1970–2025, so rates compare like for like. Over that window San Francisco warms at +0.17°F per decade, #65 of 66. The figure above uses the station’s own record, 1921–2022, so the two rates differ.

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.

Frequently asked

What is the hottest month in San Francisco?: September is San Francisco's hottest month, with the highest average daily high of the year. 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?: January is San Francisco's coldest month, with the lowest average daily low of the year. The averages-by-month chart above gives the exact average high and low for every month, 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. The warming-stripes chart above plots San Francisco's annual mean temperature for every complete year of station data from 1921 to 2022, and the trend line fitted to 1921–2022 rises about 1.4°F (+0.14°F per decade) — recent decades average warmer than the start of that window.
What is the record high temperature in San Francisco?: San Francisco's all-time record high — the hottest single day in the station record — is shown in the records section above, along with the date it occurred. Records are drawn from the nearest long-term weather station's full daily history, which begins in 1921, 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 station's full daily history back to 1921, so it reflects the coldest day on record rather than an average winter low.