May weather in Portola Valley, CA
The average temperature in Portola Valley in May is 57.0°F (47.2°F–66.9°F). Average precipitation: 1.29 inches.
May is a spring month in Portola Valley, and is cooler than the annual average of 57.1°F. Daily temperatures swing about 19.7°F between overnight low and afternoon high. Expect about 7 days with precipitation. Daylight averages about 14h 0m. For travel, May is a comfortable month to visit.
Avg High
66.9°F
Avg Low
47.2°F
Precipitation
1.29 in
Daylight
14h 0m
May records in Portola Valley
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| May 1 | 86.0°F (2014) | 37.0°F (2008) | 0.42 in (2023) |
| May 2 | 86.0°F (2013) | 36.0°F (2012) | 0.87 in (2023) |
| May 3 | 87.1°F (2017) | 37.9°F (2007) | 0.64 in (2023) |
| May 4 | 84.0°F (2004) | 37.0°F (1999) | 1.32 in (2024) |
| May 5 | 81.0°F (2021) | 35.1°F (2024) | 0.82 in (2009) |
| May 6 | 82.0°F (2011) | 35.1°F (2024) | 0.19 in (1998) |
| May 7 | 82.0°F (2020) | 37.9°F (1999) | 0.21 in (1998) |
| May 8 | 88.0°F (2020) | 37.9°F (2022) | 1.25 in (2000) |
| May 9 | 90.0°F (2001) | 36.0°F (1999) | 0.60 in (2005) |
| May 10 | 89.1°F (2001) | 33.1°F (2022) | 0.25 in (2010) |
| May 11 | 86.0°F (2001) | 35.1°F (2010) | 0.48 in (2010) |
| May 12 | 81.0°F (2013) | 37.9°F (2000) | 0.54 in (1998) |
| May 13 | 84.0°F (2014) | 35.1°F (1999) | 0.13 in (1998) |
| May 14 | 87.1°F (2014) | 36.0°F (1999) | 0.07 in (1998) |
| May 15 | 82.0°F (2006) | 34.0°F (2011) | 1.12 in (2019) |
| May 16 | 87.1°F (2008) | 37.9°F (2011) | 1.76 in (1996) |
| May 17 | 91.0°F (2008) | 37.0°F (1998) | 0.47 in (2020) |
| May 18 | 91.9°F (2009) | 34.0°F (2004) | 1.04 in (2011) |
| May 19 | 90.0°F (2008) | 39.0°F (2011) | 1.20 in (2005) |
| May 20 | 84.9°F (2017) | 35.1°F (2021) | 0.50 in (2002) |
| May 21 | 84.9°F (2001) | 37.9°F (2010) | 0.91 in (2019) |
| May 22 | 87.1°F (2000) | 35.1°F (2010) | 0.49 in (2006) |
| May 23 | 87.1°F (2000) | 35.1°F (2010) | 0.61 in (2024) |
| May 24 | 88.0°F (2022) | 37.9°F (2011) | 0.52 in (1997) |
| May 25 | 90.0°F (2020) | 39.0°F (2012) | 0.18 in (2018) |
| May 26 | 91.9°F (2020) | 39.0°F (1998) | 0.38 in (2010) |
| May 27 | 93.0°F (2020) | 39.0°F (2010) | 0.09 in (2013) |
| May 28 | 86.0°F (2018) | 39.9°F (2010) | 0.13 in (2004) |
| May 29 | 84.9°F (2003) | 36.0°F (2011) | 1.24 in (1998) |
| May 30 | 97.0°F (2025) | 39.0°F (2022) | 0.13 in (1998) |
| May 31 | 93.9°F (2025) | 41.0°F (2011) | 0.01 in (2007) |