San Carlos, CA climate
San Carlos has warm winters and pleasant summers, with very little rain. A typical July afternoon reaches 79°, a January night drops to 40°, and snow is almost unheard of.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in San Carlos feels like
Winter
Spring
Summer
Fall
San Carlos 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 | 59° | 40° | 4.5" | 0 | 9 | 0 | 46° – 54° |
| February | 61° | 42° | 4.5" | 0 | 9 | 0 | 48° – 57° |
| March | 64° | 44° | 3.5" | 0 | 9 | 0 | 49° – 59° |
| April | 67° | 45° | 1.6" | 0 | 5 | 0 | 52° – 59° |
| May | 71° | 49° | 0.7" | 0 | 3 | 0 | 56° – 65° |
| June | 76° | 51° | 0.2" | 0 | 1 | 0 | 60° – 66° |
| July | 79° | 54° | 0.0" | 0 | 0 | 0 | 63° – 70° |
| August | 79° | 54° | 0.0" | 0 | 0 | 0 | 65° – 70° |
| September | 79° | 53° | 0.1" | 0 | 1 | 0 | 63° – 70° |
| October | 74° | 49° | 1.0" | 0 | 3 | 0 | 59° – 67° |
| November | 65° | 44° | 2.3" | 0 | 6 | 0 | 49° – 57° |
| December | 59° | 40° | 4.5" | 0 | 9 | 0 | 46° – 54° |
| Year | 69° | 47° | 22.8" | 0.0" | 55 | 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 Carlos
San Carlos gets 23 inches of rain and melted snow a year. December is the wettest month and July the driest. Rain or snow falls on about 55 days a year.
A year-round growing season
Heating and cooling a home in San Carlos
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In San Carlos, 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 Carlos and its neighbors
San Carlos borders 2 towns with climate data. January nights across them vary by 3.5°. Belmont has both the coldest January nights (42°) and the hottest July afternoons (76°). San Carlos’s January low is 40° and its July high 79°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How San Carlos 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 Carlos averaged 1.7° warmer than the 1900s. The biggest change is in January (+2.2°). The shift is larger than in 83% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at San Carlos’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 49° to 59°. August is the most reliable, staying within 5°.
Common questions about San Carlos’s climate
What is the coldest month in San Carlos?
December, with a typical high of 59° and a low of 40°.
What is the hottest month in San Carlos?
August, with a typical high of 79° and a low of 54°. About 18 days a year reach 90°.
How much snow does San Carlos get?
Almost none. A normal year brings 0.0 inches.
When is the first frost in San Carlos?
Frost is uncommon. Only 88% of years see a night at 32° or below.
What is the rainiest month in San Carlos?
December, with 4.5 inches of rain and melted snow. The year totals 23 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for San Carlos itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Redwood City, CA (2 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.