San Bruno, CA climate
San Bruno has warm winters and cool summers. A typical July afternoon reaches 70°, a January night drops to 44°, and snow is almost unheard of.
NOAA 1991-2020 climate normals Updated once a decade5° warmer than normal today. The forecast high is 76°, and a typical Sep 30 in San Bruno peaks around 71°.Live forecast: National Weather Service · Normal: NOAA 1991–2020
What a year in San Bruno feels like
Winter
Spring
Summer
Fall
San Bruno 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 | 58° | 44° | 4.8" | 0 | 11 | 0 | 48° – 55° |
| February | 60° | 45° | 4.7" | 0 | 12 | 0 | 49° – 58° |
| March | 62° | 47° | 3.5" | 0 | 10 | 0 | 49° – 58° |
| April | 63° | 48° | 1.7" | 0 | 6 | 0 | 52° – 59° |
| May | 66° | 50° | 0.7" | 0 | 4 | 0 | 54° – 61° |
| June | 68° | 52° | 0.2" | 0 | 2 | 0 | 57° – 63° |
| July | 70° | 54° | 0.0" | 0 | 0 | 0 | 60° – 65° |
| August | 71° | 55° | 0.1" | 0 | 1 | 0 | 60° – 67° |
| September | 72° | 54° | 0.1" | 0 | 2 | 0 | 59° – 68° |
| October | 70° | 52° | 1.1" | 0 | 4 | 0 | 58° – 65° |
| November | 63° | 48° | 2.5" | 0 | 7 | 0 | 49° – 58° |
| December | 58° | 44° | 5.1" | 0 | 11 | 0 | 47° – 56° |
| Year | 65° | 49° | 24.5" | 0.0" | 69 | 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 Bruno
San Bruno gets 24 inches of rain and melted snow a year. December is the wettest month and July the driest. Rain or snow falls on about 69 days a year.
A year-round growing season
Heating and cooling a home in San Bruno
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In San Bruno, 96% of that work is heating and 4% 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 Bruno and its neighbors
San Bruno borders 3 towns with climate data. January nights across them vary by 1.0°. South San Francisco has both the coldest January nights (45°) and the hottest July afternoons (69°). San Bruno’s January low is 44° and its July high 70°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How San Bruno 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 Bruno averaged 1.6° warmer than the 1900s. The biggest change is in January (+2.3°). The shift is larger than in 76% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at San Bruno’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. November swings the most: between 1991 and 2020 its average temperature ranged from 49° to 58°. July is the most reliable, staying within 5°.
Common questions about San Bruno’s climate
What is the coldest month in San Bruno?
January, with a typical high of 58° and a low of 44°.
What is the hottest month in San Bruno?
September, with a typical high of 72° and a low of 54°. About 2 days a year reach 90°.
How much snow does San Bruno get?
Almost none. A normal year brings 0.0 inches.
When is the first frost in San Bruno?
Frost is uncommon. Only 20% of years see a night at 32° or below.
What is the rainiest month in San Bruno?
December, with 5.1 inches of rain and melted snow. The year totals 24 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for San Bruno itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Pacifica 4 Sse, CA (3 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.