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San Mateo, CA Weather by Month and Climate Averages
Monthly normals · Rain · Snow
Sunshine · Freeze dates · Records · Best time to visit
What is the weather like in San Mateo, CA?
San Mateo, CA gets 19.6 in of precipitation a year over about 65 rainy days. September is the warmest month (average high 74°F) and January the coldest (average low 45°F).
Mediterranean climate
San Mateo, CA has warm summers and mild winters. Daytime highs range from about 57°F in January to 74°F in September. December is usually the wettest month. The most comfortable time to visit is typically March to November, when daytime highs sit near 69°F.
| Season | Months | Avg low | Avg high |
|---|---|---|---|
| Winter | Dec–Feb | 46° | 58° |
| Spring | Mar–May | 50° | 65° |
| Summer | Jun–Aug | 55° | 72° |
| Autumn | Sep–Nov | 53° | 70° |
How much rain does San Mateo get?
San Mateo gets 19.6 in of precipitation in an average year, spread over about 65 days with measurable rain. That is fewer rainy days than 71% of the US.
December is the wettest month, with 4.1 in. July is the driest, with 0.0 in. December has the most rainy days, about 11.
The longest dry spell in the last five years lasted 119 days, to September 8, 2025.
From September 2025 to August 2026 San Mateo got 20.6 in of rain, against a normal of 19.6 in for those months. February 2026 had the most, with 4.4 in.
See where San Mateo ranks: rainiest cities in the US, US cities with the most rainy days, rainiest cities in California.
San Mateo weather by month
San Mateo weather in January
In January, San Mateo averages a high of 57°F and a low of 45°F. It gets 3.9 in of precipitation over about 11 rainy days. Estimated sunshine is 36% of daylight hours, derived from ERA5 cloud cover. The January record high is 74°F (2021) and the record low is 30°F (1975).
San Mateo weather in February
In February, San Mateo averages a high of 60°F and a low of 47°F. It gets 4.0 in of precipitation over about 11 rainy days. Estimated sunshine is 54% of daylight hours, derived from ERA5 cloud cover. The February record high is 78°F (2022) and the record low is 31°F (1989).
San Mateo weather in March
In March, San Mateo averages a high of 62°F and a low of 48°F. It gets 2.7 in of precipitation over about 10 rainy days. Estimated sunshine is 45% of daylight hours, derived from ERA5 cloud cover. The March record high is 89°F (2026) and the record low is 35°F (1971). March is one of the most comfortable months to visit.
San Mateo weather in April
In April, San Mateo averages a high of 65°F and a low of 50°F. It gets 1.4 in of precipitation over about 6 rainy days. Estimated sunshine is 53% of daylight hours, derived from ERA5 cloud cover. The April record high is 92°F (1989) and the record low is 37°F (1976). April is one of the most comfortable months to visit.
San Mateo weather in May
In May, San Mateo averages a high of 67°F and a low of 52°F. It gets 0.5 in of precipitation over about 3 rainy days. Estimated sunshine is 55% of daylight hours, derived from ERA5 cloud cover. The May record high is 97°F (1984) and the record low is 42°F (1982). May is one of the most comfortable months to visit.
San Mateo weather in June
In June, San Mateo averages a high of 71°F and a low of 54°F. It gets 0.1 in of precipitation over about 1 rainy days. Estimated sunshine is 58% of daylight hours, derived from ERA5 cloud cover. The June record high is 105°F (2000) and the record low is 46°F (1990). June is one of the most comfortable months to visit.
San Mateo weather in July
In July, San Mateo averages a high of 72°F and a low of 56°F. It gets 0.0 in of precipitation over about 0 rainy days. Estimated sunshine is 56% of daylight hours, derived from ERA5 cloud cover. The July record high is 99°F (1985) and the record low is 48°F (1998). July is one of the most comfortable months to visit.
San Mateo weather in August
In August, San Mateo averages a high of 73°F and a low of 57°F. It gets 0.0 in of precipitation over about 0 rainy days. Estimated sunshine is 57% of daylight hours, derived from ERA5 cloud cover. The August record high is 99°F (2020) and the record low is 49°F (1982). August is one of the most comfortable months to visit.
San Mateo weather in September
In September, San Mateo averages a high of 74°F and a low of 56°F. It gets 0.1 in of precipitation over about 1 rainy days. Estimated sunshine is 59% of daylight hours, derived from ERA5 cloud cover. The September record high is 104°F (2017) and the record low is 45°F (1972). September is one of the most comfortable months to visit.
San Mateo weather in October
In October, San Mateo averages a high of 72°F and a low of 54°F. It gets 0.8 in of precipitation over about 3 rainy days. Estimated sunshine is 61% of daylight hours, derived from ERA5 cloud cover. The October record high is 99°F (1987) and the record low is 39°F (1971). October is one of the most comfortable months to visit.
San Mateo weather in November
In November, San Mateo averages a high of 63°F and a low of 49°F. It gets 2.0 in of precipitation over about 7 rainy days. Estimated sunshine is 53% of daylight hours, derived from ERA5 cloud cover. The November record high is 82°F (2018) and the record low is 35°F (1978). November is one of the most comfortable months to visit.
San Mateo weather in December
In December, San Mateo averages a high of 57°F and a low of 45°F. It gets 4.1 in of precipitation over about 11 rainy days. Estimated sunshine is 34% of daylight hours, derived from ERA5 cloud cover. The December record high is 73°F (2020) and the record low is 24°F (1972).
Sunshine, humidity and wind in San Mateo
October is the sunniest month in San Mateo, with estimated sunshine of 61% of daylight hours from ERA5 cloud cover. December is the cloudiest, at 34%. The annual cloud-cover estimate is 52% of daylight hours; it is not a measurement of sunshine duration. San Mateo is sunnier than 67% of the US.
Humidity peaks in December at 82% and is lowest in October at 67%.
Wind averages 10 mph over the year, and June is the windiest month at 14 mph.
San Mateo has about 5 days a year above 90°F. San Mateo is cooler than 91% of the US.
Thunderstorms occur on about 4 days a year.
See where San Mateo ranks: sunniest cities in the US, cloudiest cities in the US, hottest cities in the US.
San Mateo weather records
These records cover SAN FRANCISCO INTL AP during 1970–2026. Earlier records or other stations in the city may differ.
The hottest temperature on record at the San Mateo station is 105°F, on June 14, 2000. The coldest is 24°F, on December 9, 1972.
The wettest day in the available station history brought 5.6 in of precipitation, on January 4, 1982.
29 all-time records have been set at the station since 1970.
The annual mean temperature has changed by +0.5°F per decade since 1970.
The best time to visit San Mateo
The most comfortable time to visit is typically March to November, when daytime highs sit near 69°F.
Winter (December–February) is mild, with average highs around 58°F and lows near 46°F.
Spring (March–May) is mild, with average highs around 65°F and lows near 50°F.
Summer (June–August) is warm, with average highs around 72°F and lows near 55°F. It can feel humid.
Autumn (September–November) is warm, with average highs around 70°F and lows near 53°F.
Monthly climate
| Month | Average low | Average high | Precip | Rain days | Wind | Humidity | Estimated sunshine | Record high | Record low |
|---|---|---|---|---|---|---|---|---|---|
| January | 45° | 57° | 3.9 in | 11 | 7 mph | 79% | 36% | 74° | 30° |
| February | 47° | 60° | 4.0 in | 11 | 8 mph | 71% | 54% | 78° | 31° |
| March | 48° | 62° | 2.7 in | 10 | 10 mph | 72% | 45% | 89° | 35° |
| April | 50° | 65° | 1.4 in | 6 | 13 mph | 72% | 53% | 92° | 37° |
| May | 52° | 67° | 0.48 in | 3 | 14 mph | 72% | 55% | 97° | 42° |
| June | 54° | 71° | 0.14 in | 1 | 14 mph | 71% | 58% | 105° | 46° |
| July | 56° | 72° | 0.00 in | 0 | 13 mph | 73% | 56% | 99° | 48° |
| August | 57° | 73° | 0.04 in | 0 | 12 mph | 73% | 57% | 99° | 49° |
| September | 56° | 74° | 0.07 in | 1 | 11 mph | 73% | 59% | 104° | 45° |
| October | 54° | 72° | 0.79 in | 3 | 9 mph | 67% | 61% | 99° | 39° |
| November | 49° | 63° | 2.0 in | 7 | 7 mph | 73% | 53% | 82° | 35° |
| December | 45° | 57° | 4.1 in | 11 | 7 mph | 82% | 34% | 73° | 24° |
Station: SAN FRANCISCO INTL AP, 7 km from the city. Temperature normal baseline: 1991–2020, calculated from available NOAA GHCN-Daily observations. Available station history: 1970–2026; record values refer to this station and period, not the entire city’s history. Precipitation includes rain and the water equivalent of frozen precipitation; snowfall depth is shown separately when available. Sources and methods
From ERA5 reanalysis. Sunshine is estimated from cloud cover.
San Mateo climate questions
How much rain does San Mateo get?
San Mateo gets 19.6 in of precipitation in an average year, over about 65 rainy days.
What is the wettest month in San Mateo?
December is the wettest month in San Mateo, with 4.1 in. July is the driest, with 0.0 in.
How many rainy days does San Mateo have a year?
San Mateo has about 65 days with measurable rain in an average year. December has the most, about 11.
What is the hottest month in San Mateo?
September is the warmest month in San Mateo, with an average high of 74°F.
What is the coldest month in San Mateo?
January is the coldest month in San Mateo, with an average low of 45°F.
What is the record high temperature in San Mateo?
Within the available 1970–2026 station history, the record high at the San Mateo station is 105°F, set on June 14, 2000. The record low is 24°F, on December 9, 1972.
What is the sunniest month in San Mateo?
October is the sunniest month in San Mateo, with estimated sunshine of 61% of daylight hours from ERA5 cloud cover. December is the cloudiest.
What is the best time to visit San Mateo?
The most comfortable time to visit is typically March to November, when daytime highs sit near 69°F.