San Anselmo, CA climate
San Anselmo has warm winters and cool summers. A typical July afternoon reaches 75°, a January night drops to 41°, and snow is almost unheard of.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in San Anselmo feels like
Winter
Spring
Summer
Fall
San Anselmo weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 57° | 41° | 6.8" | 0 | 14 | 0 | 45° – 54° |
| February | 60° | 43° | 6.8" | 0 | 13 | 0 | 47° – 57° |
| March | 62° | 44° | 4.7" | 0 | 12 | 0 | 47° – 59° |
| April | 65° | 45° | 2.1" | 0 | 9 | 0 | 51° – 58° |
| May | 68° | 48° | 1.0" | 0 | 5 | 0 | 54° – 64° |
| June | 73° | 51° | 0.2" | 0 | 4 | 0 | 59° – 64° |
| July | 75° | 52° | 0.0" | 0 | 2 | 0 | 60° – 68° |
| August | 77° | 53° | 0.1" | 0 | 3 | 0 | 62° – 68° |
| September | 77° | 52° | 0.1" | 0 | 3 | 0 | 61° – 69° |
| October | 73° | 49° | 1.5" | 0 | 6 | 0 | 58° – 66° |
| November | 63° | 45° | 3.6" | 0 | 10 | 0 | 48° – 58° |
| December | 57° | 41° | 7.4" | 0 | 15 | 0 | 45° – 53° |
| Year | 67° | 47° | 34.3" | 0.0" | 96 | 0 |
“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.
Rain and snow in San Anselmo
San Anselmo gets 34 inches of rain and melted snow a year. December is the wettest month and July the driest. Rain or snow falls on about 96 days a year.
A year-round growing season
Heating and cooling a home in San Anselmo
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In San Anselmo, 84% of that work is heating and 16% is cooling, so the furnace matters far more than the air conditioner.
Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.
San Anselmo and its neighbors
San Anselmo borders 4 towns with climate data. January nights across them vary by 2.2°. Sleepy Hollow has both the coldest January nights (41°) and the hottest July afternoons (76°). San Anselmo’s January low is 41° and its July high 75°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How San Anselmo compares
Compared with every U.S. town and city on TownTapestry, each counted once.
Warmer than it used to be
The last 30 years in San Anselmo averaged 1.4° warmer than the 1900s. The biggest change is in January (+2.3°). The shift is larger than in 67% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at San Anselmo’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. March swings the most: between 1991 and 2020 its average temperature ranged from 47° to 59°. June is the most reliable, staying within 6°.
Common questions about San Anselmo’s climate
What is the coldest month in San Anselmo?
January, with a typical high of 57° and a low of 41°.
What is the hottest month in San Anselmo?
September, with a typical high of 77° and a low of 52°. About 20 days a year reach 90°.
How much snow does San Anselmo get?
Almost none. A normal year brings 0.0 inches.
When is the first frost in San Anselmo?
Frost is uncommon. Only 70% of years see a night at 32° or below.
What is the rainiest month in San Anselmo?
December, with 7.4 inches of rain and melted snow. The year totals 34 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for San Anselmo itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Muir Woods, CA (6 mi, snow) and San Rafael Civic Ctr, CA (2 mi, frost, heat and degree days). Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.