December weather in Diamond Bar, CA
The average temperature in Diamond Bar in December is 54.2°F (41.5°F–66.9°F). Average precipitation: 2.29 inches.
December is a winter month in Diamond Bar, and is cooler than the annual average of 65.1°F. Daily temperatures swing about 25.4°F between overnight low and afternoon high. Expect about 5 days with precipitation. Daylight averages about 9h 45m. For travel, December is a comfortable month to visit.
Avg High
66.9°F
Avg Low
41.5°F
Precipitation
2.29 in
Daylight
9h 45m
December records in Diamond Bar
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| December 1 | 86.0°F (1959) | 28.0°F (1931) | 0.62 in (1923) |
| December 2 | 88.0°F (1958) | 26.1°F (1936) | 1.74 in (1961) |
| December 3 | 91.9°F (1958) | 27.0°F (1934) | 2.61 in (1966) |
| December 4 | 93.0°F (1979) | 28.0°F (1948) | 3.00 in (2004) |
| December 5 | 90.0°F (1979) | 26.1°F (1948) | 2.79 in (1966) |
| December 6 | 89.1°F (1938) | 27.0°F (1920) | 2.37 in (1966) |
| December 7 | 86.0°F (1938) | 25.0°F (1951) | 0.62 in (1972) |
| December 8 | 89.1°F (1938) | 25.0°F (1951) | 1.53 in (1894) |
| December 9 | 84.0°F (1975) | 23.0°F (1951) | 1.65 in (1931) |
| December 10 | 86.0°F (1958) | 26.1°F (1951) | 1.16 in (1927) |
| December 11 | 88.0°F (1958) | 27.0°F (1916) | 2.26 in (1943) |
| December 12 | 84.9°F (1895) | 25.0°F (1949) | 2.05 in (1906) |
| December 13 | 84.9°F (1958) | 24.1°F (1901) | 1.74 in (1933) |
| December 14 | 84.0°F (1953) | 25.0°F (1901) | 2.20 in (1922) |
| December 15 | 84.9°F (1980) | 27.0°F (1948) | 2.02 in (1957) |
| December 16 | 84.9°F (1980) | 27.0°F (1915) | 2.85 in (1988) |
| December 17 | 86.0°F (1979) | 26.1°F (1916) | 2.27 in (1940) |
| December 18 | 84.0°F (1917) | 26.1°F (1924) | 2.50 in (1978) |
| December 19 | 84.9°F (1985) | 26.1°F (1897) | 3.15 in (1938) |
| December 20 | 84.0°F (1985) | 28.0°F (1897) | 1.57 in (2010) |
| December 21 | 84.0°F (1917) | 23.0°F (1968) | 2.42 in (1921) |
| December 22 | 81.0°F (1960) | 21.9°F (1990) | 3.03 in (1945) |
| December 23 | 82.0°F (1989) | 26.1°F (1990) | 3.05 in (1945) |
| December 24 | 86.0°F (2005) | 24.1°F (1953) | 2.35 in (1940) |
| December 25 | 84.9°F (1980) | 25.0°F (1924) | 2.54 in (1971) |
| December 26 | 87.1°F (1980) | 25.0°F (1924) | 1.94 in (1983) |
| December 27 | 82.0°F (1956) | 24.1°F (1962) | 1.25 in (1964) |
| December 28 | 84.9°F (1956) | 24.1°F (1954) | 2.70 in (1906) |
| December 29 | 88.0°F (1980) | 24.1°F (1954) | 2.45 in (1931) |
| December 30 | 84.9°F (1980) | 24.1°F (1918) | 4.07 in (1951) |
| December 31 | 82.0°F (1897) | 25.0°F (1918) | 3.50 in (2004) |