Weather history and climate summary information is available for the following locations:
- Casper
- Cheyenne
- Sheridan
Warmest December Days
The warmest December days in Wyoming are:
| Sheridan, Wyoming | 1981 | 72°F |
| Sheridan, Wyoming | 1999 | 71.1°F |
| Sheridan, Wyoming | 1975 | 70°F |
| Sheridan, Wyoming | 1995 | 70°F |
| Sheridan, Wyoming | 1979 | 69.1°F |
Coldest December Days
The coldest December days in Wyoming were:
| Casper, Wyoming | 1990 | -41.1°F |
| Casper, Wyoming | 1983 | -38.9°F |
| Sheridan, Wyoming | 1989 | -35.1°F |
| Sheridan, Wyoming | 1983 | -35°F |
| Casper, Wyoming | 1978 | -34.1°F |
Wettest December Days
The wettest single days in December occurred:
| Sheridan, Wyoming | 1989 | 2.1 inches |
| Casper, Wyoming | 1982 | 1.5 inches |
| Cheyenne, Wyoming | 1979 | 1.1 inches |
| Sheridan, Wyoming | 1975 | 0.9 inches |
| Cheyenne, Wyoming | 2006 | 0.8 inches |