January weather in San Marcos, CA
The average temperature in San Marcos in January is 56.8°F (44.8°F–68.8°F). Average precipitation: 3.19 inches.
January is a winter month in San Marcos, and is cooler than the annual average of 65.8°F. Daily temperatures swing about 24°F between overnight low and afternoon high. Expect about 6 days with precipitation. Daylight averages about 10h 2m. For travel, January is a comfortable month to visit.
Avg High
68.8°F
Avg Low
44.8°F
Precipitation
3.19 in
Daylight
10h 2m
January records in San Marcos
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| January 1 | 84.0°F (2012) | 30.0°F (1983) | 2.15 in (2023) |
| January 2 | 82.0°F (2012) | 30.9°F (1983) | 1.15 in (2006) |
| January 3 | 82.0°F (1994) | 30.0°F (1982) | 0.90 in (2005) |
| January 4 | 88.0°F (2012) | 27.0°F (2008) | 0.72 in (2005) |
| January 5 | 84.9°F (2006) | 33.1°F (2013) | 1.95 in (1995) |
| January 6 | 87.1°F (2015) | 27.0°F (2008) | 1.35 in (1993) |
| January 7 | 82.0°F (1996) | 30.0°F (1989) | 3.10 in (1993) |
| January 8 | 86.0°F (2007) | 30.9°F (1982) | 1.14 in (1995) |
| January 9 | 86.0°F (1990) | 30.9°F (1989) | 2.10 in (2018) |
| January 10 | 81.0°F (1990) | 30.0°F (1989) | 1.86 in (1998) |
| January 11 | 86.0°F (1996) | 32.0°F (2013) | 2.57 in (1980) |
| January 12 | 84.9°F (1996) | 32.0°F (2013) | 0.95 in (1995) |
| January 13 | 84.9°F (2018) | 30.9°F (2007) | 2.15 in (1997) |
| January 14 | 89.1°F (2021) | 30.9°F (1989) | 1.51 in (1993) |
| January 15 | 91.0°F (2021) | 25.0°F (2007) | 1.80 in (2023) |
| January 16 | 88.0°F (2021) | 30.0°F (1987) | 2.34 in (2023) |
| January 17 | 87.1°F (2014) | 27.0°F (1987) | 0.93 in (1990) |
| January 18 | 86.0°F (2026) | 30.9°F (1984) | 1.35 in (1993) |
| January 19 | 84.0°F (1989) | 34.0°F (2002) | 0.89 in (2017) |
| January 20 | 81.0°F (2005) | 30.9°F (1988) | 1.56 in (2017) |
| January 21 | 81.0°F (2014) | 30.0°F (1987) | 0.99 in (1982) |
| January 22 | 86.0°F (2025) | 32.0°F (1987) | 1.88 in (2024) |
| January 23 | 78.1°F (1990) | 33.1°F (1982) | 1.87 in (2017) |
| January 24 | 84.0°F (1988) | 32.0°F (2007) | 0.52 in (2017) |
| January 25 | 84.9°F (2003) | 35.1°F (1993) | 0.86 in (1994) |
| January 26 | 86.0°F (1987) | 34.0°F (1981) | 1.25 in (1997) |
| January 27 | 84.9°F (2003) | 37.9°F (1980) | 1.08 in (1983) |
| January 28 | 84.9°F (2003) | 28.0°F (2005) | 0.72 in (1980) |
| January 29 | 88.0°F (2018) | 34.0°F (1999) | 3.24 in (1980) |
| January 30 | 89.1°F (2026) | 30.0°F (2002) | 0.88 in (1980) |
| January 31 | 91.9°F (2003) | 28.0°F (2002) | 1.14 in (2016) |