Portola Valley Weather in May
Average highs run from 71°F on May 1 to 76°F on May 31, and lows from 48°F to 52°F. Normal precipitation for the month is 0.46 in over about 3 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
- 73°F
- Average low
- 50°F
- Precipitation
- 0.46 in
- Record high
- 100°FMay 13, 1976
- Record low
- 33°FMay 6, 1977
- Chance of a freeze
- 0%
- Days of 90°F or more
- 1.2
- Daylight
- 13 h 45 min to 14 h 34 min
- Cloud cover
- 33%
- Humidity
- 74%
- Dew point
- 48°F
- Wind
- 8.5 mph
Every day of the month
A wet day has at least 0.01 inch of precipitation; snow means at least 0.1 inch of snowfall.
| Date | Normal high | Normal low | Record high | Record low | Chance wet | Chance of snow |
|---|---|---|---|---|---|---|
| May 1 | 71°F | 48°F | 96°F 1996 | 38°F 1954 | 12% | 0% |
| May 2 | 71°F | 49°F | 94°F 1996 | 37°F 1982 | 12% | 0% |
| May 3 | 71°F | 49°F | 93°F 1970 | 37°F 1982 | 12% | 0% |
| May 4 | 71°F | 49°F | 92°F 2017 | 35°F 1982 | 11% | 0% |
| May 5 | 71°F | 49°F | 91°F 2017 | 40°F 1960 | 11% | 0% |
| May 6 | 71°F | 49°F | 95°F 1987 | 33°F 1977 | 11% | 0% |
| May 7 | 71°F | 49°F | 94°F 1987 | 37°F 1964 | 11% | 0% |
| May 8 | 72°F | 49°F | 95°F 1987 | 40°F 1964 | 10% | 0% |
| May 9 | 72°F | 50°F | 96°F 1990 | 40°F 1963 | 10% | 0% |
| May 10 | 72°F | 50°F | 88°F 1993 | 40°F 1982 | 10% | 0% |
| May 11 | 72°F | 50°F | 87°F 1955 | 37°F 1982 | 10% | 0% |
| May 12 | 72°F | 50°F | 90°F 1996 | 34°F 1982 | 10% | 0% |
| May 13 | 72°F | 50°F | 100°F 1976 | 39°F 1977 | 10% | 0% |
| May 14 | 72°F | 50°F | 94°F 2014 | 40°F 1964 | 9% | 0% |
| May 15 | 73°F | 50°F | 91°F 1976 | 38°F 1964 | 9% | 0% |
| May 16 | 73°F | 51°F | 97°F 1970 | 39°F 2002 | 9% | 0% |
| May 17 | 73°F | 51°F | 99°F 1956 | 39°F 1977 | 9% | 0% |
| May 18 | 73°F | 51°F | 100°F 1997 | 38°F 1977 | 9% | 0% |
| May 19 | 73°F | 51°F | 95°F 1978 | 41°F 1991 | 8% | 0% |
| May 20 | 74°F | 51°F | 93°F 1990 | 42°F 1976 | 8% | 0% |
| May 21 | 74°F | 51°F | 98°F 1990 | 40°F 1982 | 8% | 0% |
| May 22 | 74°F | 51°F | 91°F 1988 | 41°F 1960 | 8% | 0% |
| May 23 | 74°F | 51°F | 90°F 1954 | 40°F 2010 | 8% | 0% |
| May 24 | 74°F | 52°F | 94°F 1970 | 37°F 1978 | 7% | 0% |
| May 25 | 74°F | 52°F | 97°F 1982 | 42°F 1961 | 7% | 0% |
| May 26 | 75°F | 52°F | 90°F 1975 | 44°F 2008 | 7% | 0% |
| May 27 | 75°F | 52°F | 95°F 1974 | 42°F 1961 | 7% | 0% |
| May 28 | 75°F | 52°F | 97°F 1984 | 40°F 1977 | 7% | 0% |
| May 29 | 75°F | 52°F | 94°F 1975 | 42°F 1961 | 6% | 0% |
| May 30 | 76°F | 52°F | 96°F 1978 | 42°F 1983 | 6% | 0% |
| May 31 | 76°F | 52°F | 95°F 1978 | 45°F 1955 | 6% | 0% |
Chance of rain
- Chance of a wet day
- Chance of snowfall
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 USC00047339 (Redwood City), public domain. Records: NOAA GHCN-Daily, station USC00046646, 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.