Weather history and climate summary information is available for the following locations:
- Bellingham
- Grant County Airport
- Seattle
- Spokane
- Tacoma
- Walla Walla
- Yakima
Warmest December Days
The warmest December days in Washington are:
| Grant County Airport, Washington | 1998 | 68°F |
| Walla Walla, Washington | 1980 | 68°F |
| Yakima, Washington | 1974 | 66.9°F |
| Tacoma, Washington | 1993 | 66.9°F |
| Walla Walla, Washington | 2002 | 66.2°F |
Coldest December Days
The coldest December days in Washington were:
| Spokane, Washington | 1978 | -22°F |
| Spokane, Washington | 1964 | -18.9°F |
| Spokane, Washington | 1983 | -18°F |
| Spokane, Washington | 2008 | -18°F |
| Spokane, Washington | 1968 | -17.9°F |
Wettest December Days
The wettest single days in December occurred:
| Tacoma, Washington | 1994 | 2.8 inches |
| Seattle, Washington | 2007 | 2.7 inches |
| Seattle, Washington | 2007 | 2.7 inches |
| Tacoma, Washington | 1941 | 2.4 inches |
| Seattle, Washington | 2010 | 2.3 inches |