May weather in San Marcos, CA
The average temperature in San Marcos in May is 66.6°F (56.4°F–76.7°F). Average precipitation: 0.35 inches.
May is a spring month in San Marcos, and is warmer than the annual average of 65.8°F. Daily temperatures swing about 20.3°F between overnight low and afternoon high. Expect about 3 days with precipitation. Daylight averages about 13h 43m. For travel, May is one of the best months of the year to visit.
Avg High
76.7°F
Avg Low
56.4°F
Precipitation
0.35 in
Daylight
13h 43m
May records in San Marcos
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| May 1 | 93.9°F (2014) | 42.1°F (1999) | 0.30 in (1983) |
| May 2 | 100.0°F (2004) | 44.1°F (1988) | 0.09 in (1980) |
| May 3 | 102.9°F (2004) | 44.1°F (1988) | 0.52 in (2003) |
| May 4 | 91.0°F (2011) | 48.0°F (1988) | 0.25 in (2023) |
| May 5 | 97.0°F (1990) | 46.9°F (1999) | 0.12 in (2024) |
| May 6 | 99.0°F (1990) | 30.9°F (2003) | 0.55 in (2013) |
| May 7 | 97.0°F (2020) | 46.0°F (1983) | 0.83 in (2017) |
| May 8 | 95.0°F (2007) | 41.0°F (1986) | 0.54 in (2015) |
| May 9 | 93.9°F (2025) | 46.0°F (1979) | 0.07 in (1994) |
| May 10 | 99.0°F (2025) | 42.1°F (2003) | 0.09 in (1980) |
| May 11 | 93.9°F (1996) | 46.0°F (2003) | 0.07 in (1982) |
| May 12 | 96.1°F (2013) | 44.1°F (1982) | 0.58 in (1998) |
| May 13 | 100.9°F (2013) | 48.0°F (1980) | 0.35 in (1998) |
| May 14 | 99.0°F (1979) | 42.1°F (1981) | 0.08 in (1980) |
| May 15 | 104.0°F (2014) | 41.0°F (2003) | 0.47 in (2015) |
| May 16 | 100.9°F (2014) | 35.1°F (2003) | 0.25 in (2019) |
| May 17 | 91.9°F (2014) | 33.1°F (2003) | 0.25 in (2011) |
| May 18 | 90.0°F (1983) | 33.1°F (2000) | 0.34 in (2011) |
| May 19 | 90.0°F (2017) | 46.9°F (1994) | 0.39 in (2019) |
| May 20 | 93.9°F (2017) | 30.9°F (2003) | 0.38 in (2019) |
| May 21 | 95.0°F (2005) | 45.0°F (1981) | 0.10 in (2002) |
| May 22 | 90.0°F (1988) | 46.0°F (2002) | 0.17 in (2015) |
| May 23 | 97.0°F (2001) | 48.0°F (2002) | 0.18 in (1992) |
| May 24 | 87.1°F (1993) | 46.9°F (1980) | 0.04 in (1997) |
| May 25 | 88.0°F (2021) | 45.0°F (1980) | 0.09 in (2012) |
| May 26 | 88.0°F (2020) | 44.1°F (1980) | 0.06 in (2000) |
| May 27 | 91.0°F (2000) | 48.9°F (1980) | 0.10 in (2019) |
| May 28 | 97.0°F (1997) | 43.0°F (2003) | 0.80 in (1990) |
| May 29 | 96.1°F (1997) | 46.9°F (1980) | 0.16 in (1988) |
| May 30 | 96.1°F (2025) | 48.9°F (1988) | 0.05 in (2023) |
| May 31 | 93.0°F (2004) | 48.0°F (1988) | 0.12 in (2023) |