San Mateo County Weather in May
Average highs run from 61°F on May 1 to 63°F on May 31, and lows from 46°F to 49°F. Normal precipitation for the month is 0.96 in over about 7 wet days.
May day by day
The normal high and low for each date, and the record, in °F.
- Normal low
- Normal high
- Record high
- Record low
May at a glance
- Average high
- 62°F
- Average low
- 48°F
- Precipitation
- 0.96 in
- Record high
- 102°FMay 29, 1950
- Record low
- 36°FMay 4, 1950
- Chance of a freeze
- 0%
- Daylight
- 13 h 45 min to 14 h 34 min
- Cloud cover
- 54%
- Humidity
- 85%
- Dew point
- 50°F
- Wind
- 11.0 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 |
|---|---|---|---|---|---|
| May 1 | 61°F | 46°F | 95°F 1947 | 38°F 1967 | 24% |
| May 2 | 61°F | 46°F | 92°F 2013 | 40°F 1950 | 24% |
| May 3 | 61°F | 47°F | 93°F 2017 | 38°F 1939 | 24% |
| May 4 | 61°F | 47°F | 91°F 1990 | 36°F 1950 | 24% |
| May 5 | 61°F | 47°F | 95°F 1987 | 37°F 1952 | 24% |
| May 6 | 61°F | 47°F | 96°F 1987 | 38°F 1968 | 23% |
| May 7 | 61°F | 47°F | 95°F 1987 | 38°F 1975 | 23% |
| May 8 | 61°F | 47°F | 93°F 2001 | 36°F 1933 | 23% |
| May 9 | 61°F | 47°F | 93°F 1931 | 40°F 1933 | 23% |
| May 10 | 61°F | 47°F | 93°F 1934 | 38°F 1933 | 23% |
| May 11 | 61°F | 48°F | 95°F 1934 | 40°F 1982 | 23% |
| May 12 | 61°F | 48°F | 101°F 1976 | 40°F 1948 | 23% |
| May 13 | 61°F | 48°F | 100°F 1976 | 40°F 1977 | 23% |
| May 14 | 62°F | 48°F | 95°F 1972 | 36°F 1933 | 23% |
| May 15 | 62°F | 48°F | 97°F 1970 | 39°F 1932 | 23% |
| May 16 | 62°F | 48°F | 98°F 1997 | 40°F 1955 | 23% |
| May 17 | 62°F | 48°F | 96°F 2009 | 40°F 1977 | 23% |
| May 18 | 62°F | 48°F | 92°F 1952 | 39°F 1933 | 23% |
| May 19 | 62°F | 49°F | 92°F 1952 | 36°F 1933 | 23% |
| May 20 | 62°F | 49°F | 94°F 1942 | 42°F 1945 | 23% |
| May 21 | 62°F | 49°F | 94°F 1988 | 40°F 1974 | 22% |
| May 22 | 62°F | 49°F | 95°F 1943 | 42°F 1949 | 22% |
| May 23 | 62°F | 49°F | 98°F 1943 | 41°F 1975 | 22% |
| May 24 | 62°F | 49°F | 100°F 1982 | 42°F 1961 | 22% |
| May 25 | 62°F | 49°F | 99°F 1982 | 40°F 1980 | 22% |
| May 26 | 62°F | 49°F | 98°F 1974 | 40°F 1980 | 22% |
| May 27 | 63°F | 49°F | 98°F 1984 | 43°F 1961 | 22% |
| May 28 | 63°F | 49°F | 96°F 1984 | 41°F 1977 | 21% |
| May 29 | 63°F | 49°F | 102°F 1950 | 40°F 1940 | 21% |
| May 30 | 63°F | 49°F | 101°F 1950 | 43°F 1935 | 21% |
| May 31 | 63°F | 49°F | 99°F 2001 | 42°F 1933 | 21% |
Chance of rain
- Chance of a wet day
Sunrise and sunset
Times for 2026, local time (PDT).
- May 1
- sunrise 6:14 AM, sunset 7:59 PM
- May 31
- sunrise 5:50 AM, sunset 8:24 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.