San Francisco averages 22.89 inches of rain per year at its downtown weather station, spread over about 71 days with measurable rain. Nearly all of that rain falls from November through March, and December is the wettest month at 4.76 inches. San Francisco gets less rain than New York (49.52 inches) or Seattle (39.34 inches), and more than downtown Los Angeles (14.25 inches).
How Much Rain Does San Francisco Get Each Year?
San Francisco gets 22.89 inches of rain in an average year, based on NOAA's 1991-2020 normal for the downtown station. The 2025-26 water year, which ended September 30, 2026, finished at 20.76 inches, or 91% of normal. San Francisco measures rain by water year, from October 1 to September 30, so each total covers one full winter.
Single years can swing far from the average. The wettest water year on record is 1861-62, with 49.25 inches during the Great Flood of 1862, followed by 46.56 inches during the 1997-98 El Niño. The driest water years are 1850-51 (8.14 inches) and 2020-21 (9.04 inches), and calendar year 2013 brought only 5.59 inches.
How Many Days Does It Rain in San Francisco?
San Francisco gets measurable rain on about 71 days a year, or roughly one day in five. Only about 45 of those days bring a tenth of an inch or more, enough to soak streets and cancel outdoor plans. The rest bring only drizzle or light showers.
The rainy days cluster in winter, when December, January, February and March each average about 11 rainy days, so roughly one winter day in three is wet. July averages less than one rainy day, and June through September together average under five.
San Francisco does not get a lot of rain by volume, and it gets almost none in summer. The city's rainy reputation comes from winter, when atmospheric rivers can bring several wet days in a row. Summer gray days are usually fog, not rain, as our guide to what the marine layer is explains.
How Much Rain Does San Francisco Get Each Month?
December is San Francisco's wettest month, averaging 4.76 inches, followed by January (4.40 inches) and February (4.37 inches). November through March brings 19.28 inches, or 84% of the yearly total, while July, the driest month, averages just 0.01 inch.
| Month | Average rainfall (inches) | Average rainy days |
|---|---|---|
| January | 4.40 | 11.2 |
| February | 4.37 | 10.7 |
| March | 3.15 | 10.8 |
| April | 1.60 | 6.8 |
| May | 0.70 | 4.0 |
| June | 0.20 | 1.6 |
| July | 0.01 | 0.7 |
| August | 0.06 | 1.1 |
| September | 0.10 | 1.2 |
| October | 0.94 | 3.5 |
| November | 2.60 | 7.9 |
| December | 4.76 | 11.7 |
| Year | 22.89 | 71.2 |
San Francisco Downtown station. Rainfall is the NOAA 1991-2020 normal. Rainy days are days with at least 0.01 inch, averaged over 1991-2020. Source: NOAA station records via RCC-ACIS.
What Is the Most Rain San Francisco Has Gotten in One Day?
The most rain San Francisco has recorded in one day is 5.54 inches, on November 5, 1994. The second-wettest day is December 31, 2022, when an atmospheric river dropped 5.46 inches. Days like these flood low-lying streets and overwhelm the city's combined sewer system. For the biggest storms across the region, see the most rain in a single day in the Bay Area.
Does Rainfall Vary Across San Francisco?
Rainfall varies only modestly across San Francisco. The western hills and higher neighborhoods (Twin Peaks, Mount Davidson and Sunset Heights) get slightly more rain than the bay-facing east side. Storms approach from the west, and the hills lift the air and squeeze out a little more rain, a process called orographic enhancement.
The difference is about 2 to 4 inches per year, smaller than the city's microclimate temperature differences but measurable. The Mission District, sheltered by Twin Peaks, gets slightly less rain than the Outer Sunset.
How Much Does San Francisco Rainfall Change From Year to Year?
San Francisco rainfall changes a lot from year to year, and the wettest water year on record brought six times as much rain as the driest. The 2012-2016 drought was one of the most severe in California's modern record. The 2022-23 winter swung the other way, when atmospheric rivers brought 33.87 inches, 148% of normal.
These swings are a defining feature of the Bay Area's Mediterranean climate, with a wet season that can bring feast or famine. For planning, expect rain from November through March, assume summer is dry, and check the El Niño outlook to know what kind of winter is coming.
