| 2023 Hardiness Zone: | Zone 5a: -20°F to -15°F | |
| 2012 Hardiness Zone: | Zone 5a: -20°F to -15°F Zone 4b: -25°F to -20°F | |
| 1990 Hardiness Zone: | Zone 4a: -30F to -25F | |
| Average First Frost Date: | Sep. 21 - Sep. 30 | |
| Average Last Frost Date: | May 11 - May 20 | |
| Koppen-Geiger Climate Zone: | Dfb - Humid Continental Mild Summer, Wet All Year | |
| Ecoregion: | 43w - Powder River Basin | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | 15 - 30 days Over 86°F |
Annual Climate Data for ZIP Code 82609 - Casper, WY | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 14 | 19 | 25 | 31 | 39 | 48 | 54 | 52 | 42 | 33 | 23 | 17 | 33 |
| Avg Max Temp (°F) | 35 | 39 | 48 | 56 | 67 | 78 | 86 | 85 | 74 | 61 | 44 | 36 | 59 |
| Avg Precip (In.) | .49 | .56 | .88 | 1.58 | 2.61 | 1.36 | 1.21 | .78 | 1 | 1.14 | .81 | .59 | 13.01 |