December weather in Foster City, CA
The average temperature in Foster City in December is 49.4°F (40.2°F–58.6°F). Average precipitation: 3.92 inches.
December is a winter month in Foster City, and is cooler than the annual average of 59.4°F. Daily temperatures swing about 18.4°F between overnight low and afternoon high. Expect about 9 days with precipitation. Daylight averages about 9h 25m. For travel, December is a comfortable month to visit.
Avg High
58.6°F
Avg Low
40.2°F
Precipitation
3.92 in
Daylight
9h 25m
December records in Foster City
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| December 1 | 73.0°F (1943) | 30.0°F (1931) | 2.49 in (1952) |
| December 2 | 75.0°F (1941) | 30.0°F (1936) | 1.97 in (2014) |
| December 3 | 73.0°F (1959) | 28.0°F (1936) | 2.15 in (1950) |
| December 4 | 73.9°F (1958) | 28.0°F (1936) | 2.19 in (1915) |
| December 5 | 73.0°F (1976) | 27.0°F (2013) | 1.95 in (1909) |
| December 6 | 75.0°F (2024) | 28.0°F (1931) | 1.17 in (1992) |
| December 7 | 75.0°F (1934) | 21.9°F (1998) | 2.76 in (1952) |
| December 8 | 75.0°F (2024) | 25.0°F (1978) | 1.50 in (1909) |
| December 9 | 73.9°F (1934) | 21.9°F (1972) | 1.15 in (1908) |
| December 10 | 71.1°F (1934) | 25.0°F (1972) | 2.00 in (1937) |
| December 11 | 72.0°F (1958) | 23.0°F (1932) | 4.19 in (2014) |
| December 12 | 75.9°F (1958) | 18.0°F (1932) | 2.43 in (1995) |
| December 13 | 70.0°F (1953) | 19.0°F (1932) | 2.09 in (2021) |
| December 14 | 71.1°F (1958) | 21.9°F (1932) | 2.67 in (1915) |
| December 15 | 72.0°F (1980) | 19.9°F (1932) | 1.86 in (1957) |
| December 16 | 73.9°F (1998) | 26.1°F (1932) | 2.15 in (2002) |
| December 17 | 73.0°F (1958) | 27.0°F (1965) | 1.40 in (1977) |
| December 18 | 70.0°F (1998) | 27.0°F (1965) | 1.06 in (1970) |
| December 19 | 70.0°F (1999) | 28.9°F (1935) | 3.04 in (1955) |
| December 20 | 71.1°F (1944) | 28.0°F (1965) | 1.58 in (1981) |
| December 21 | 70.0°F (1999) | 24.1°F (1968) | 1.94 in (1982) |
| December 22 | 68.0°F (1999) | 19.0°F (1990) | 2.56 in (1982) |
| December 23 | 69.1°F (2014) | 21.0°F (1990) | 4.00 in (1955) |
| December 24 | 72.0°F (2013) | 21.9°F (1990) | 1.32 in (1931) |
| December 25 | 75.0°F (1967) | 25.0°F (1998) | 1.93 in (2008) |
| December 26 | 73.9°F (1967) | 25.0°F (1998) | 1.82 in (1948) |
| December 27 | 75.0°F (1967) | 28.0°F (1990) | 2.83 in (1931) |
| December 28 | 73.9°F (1967) | 26.1°F (1930) | 1.41 in (1951) |
| December 29 | 72.0°F (2025) | 21.9°F (1930) | 2.46 in (1981) |
| December 30 | 69.1°F (1958) | 24.1°F (1930) | 1.06 in (1907) |
| December 31 | 70.0°F (1958) | 28.0°F (1990) | 4.47 in (2022) |