San Mateo County Weather in January
Average highs run from 59°F on January 1 to 60°F on January 31, and lows from 43°F to 43°F. Normal precipitation for the month is 5.07 in over about 14 wet days.
January day by day
The normal high and low for each date, and the record, in °F.
- Normal low
- Normal high
- Record high
- Record low
January at a glance
- Average high
- 59°F
- Average low
- 43°F
- Precipitation
- 5.07 in
- Record high
- 78°FJan 13, 2009
- Record low
- 16°FJan 11, 1949
- Chance of a freeze
- 30%
- Daylight
- 9 h 38 min to 10 h 20 min
- Cloud cover
- 60%
- Humidity
- 84%
- Dew point
- 46°F
- Wind
- 10.1 mph
Every day of the month
A wet day has at least 0.01 inch of precipitation.
| Date | Normal high | Normal low | Record high | Record low | Chance wet |
|---|---|---|---|---|---|
| Jan 1 | 59°F | 43°F | 67°F 1996 | 27°F 1933 | 45% |
| Jan 2 | 59°F | 43°F | 71°F 1996 | 24°F 1960 | 45% |
| Jan 3 | 59°F | 43°F | 71°F 1996 | 25°F 1976 | 45% |
| Jan 4 | 59°F | 43°F | 69°F 1946 | 25°F 1947 | 45% |
| Jan 5 | 59°F | 43°F | 69°F 2014 | 22°F 1949 | 45% |
| Jan 6 | 59°F | 43°F | 70°F 2003 | 24°F 1950 | 45% |
| Jan 7 | 59°F | 43°F | 73°F 1962 | 23°F 1937 | 46% |
| Jan 8 | 59°F | 43°F | 75°F 1962 | 22°F 1937 | 46% |
| Jan 9 | 59°F | 43°F | 75°F 2025 | 19°F 1937 | 46% |
| Jan 10 | 59°F | 44°F | 70°F 1941 | 23°F 1949 | 46% |
| Jan 11 | 59°F | 44°F | 70°F 1959 | 16°F 1949 | 46% |
| Jan 12 | 59°F | 44°F | 76°F 2009 | 26°F 1949 | 46% |
| Jan 13 | 59°F | 44°F | 78°F 2009 | 24°F 1963 | 46% |
| Jan 14 | 59°F | 44°F | 77°F 2026 | 26°F 2007 | 46% |
| Jan 15 | 60°F | 44°F | 78°F 2009 | 27°F 1963 | 46% |
| Jan 16 | 60°F | 44°F | 77°F 2026 | 26°F 1947 | 46% |
| Jan 17 | 60°F | 44°F | 77°F 1948 | 25°F 1933 | 46% |
| Jan 18 | 60°F | 44°F | 76°F 2021 | 27°F 1943 | 46% |
| Jan 19 | 60°F | 44°F | 73°F 1976 | 26°F 1943 | 46% |
| Jan 20 | 60°F | 44°F | 73°F 1976 | 27°F 1963 | 46% |
| Jan 21 | 60°F | 44°F | 70°F 1976 | 20°F 1937 | 46% |
| Jan 22 | 60°F | 44°F | 75°F 1968 | 22°F 1937 | 46% |
| Jan 23 | 60°F | 43°F | 78°F 1948 | 22°F 1937 | 46% |
| Jan 24 | 60°F | 43°F | 75°F 1948 | 26°F 1932 | 46% |
| Jan 25 | 60°F | 43°F | 72°F 2011 | 24°F 1937 | 46% |
| Jan 26 | 60°F | 43°F | 71°F 2014 | 25°F 1949 | 46% |
| Jan 27 | 60°F | 43°F | 70°F 1934 | 28°F 1948 | 46% |
| Jan 28 | 60°F | 43°F | 73°F 2024 | 26°F 1948 | 46% |
| Jan 29 | 60°F | 43°F | 72°F 1931 | 27°F 1979 | 46% |
| Jan 30 | 60°F | 43°F | 72°F 1976 | 25°F 1975 | 46% |
| Jan 31 | 60°F | 43°F | 75°F 2015 | 26°F 1946 | 46% |
Chance of rain
- Chance of a wet day
Sunrise and sunset
Times for 2026, local time (PST).
- January 1
- sunrise 7:24 AM, sunset 5:02 PM
- January 31
- sunrise 7:13 AM, sunset 5:33 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00043714 (Half Moon Bay), public domain. Records: NOAA GHCN-Daily, station USC00047339, every year on file, quality-flagged values removed. Cloud, humidity, wind and sunshine: NASA POWER (MERRA-2, CERES and GEWEX SRB), 1991-2020. The data was obtained from the National Aeronautics and Space Administration (NASA) Langley Research Center's Prediction Of Worldwide Energy Resources (POWER) project funded through the NASA Earth Science Division: POWER Daily API v2, accessed 2026-09-24. Sun and moon: computed with the NOAA solar equations and Meeus.