| 2023 Hardiness Zone: | Zone 5a: -20°F to -15°F Zone 4b: -25°F to -20°F Zone 5b: -15°F to -10°F | |
| 2012 Hardiness Zone: | Zone 5a: -20°F to -15°F Zone 4b: -25°F to -20°F Zone 4a: -30°F to -25°F | |
| 1990 Hardiness Zone: | Zone 4a: -30F to -25F | |
| Average First Frost Date: | Sep. 21 - Sep. 30 | |
| Average Last Frost Date: | May 21 - May 31 | |
| Koppen-Geiger Climate Zone: | BSk - Cold Semi-Arid Climate | |
| 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 82718 - Gillette, WY | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 10 | 15 | 21 | 29 | 38 | 47 | 54 | 53 | 42 | 32 | 20 | 12 | 31 |
| Avg Max Temp (°F) | 31 | 37 | 45 | 55 | 65 | 76 | 85 | 84 | 73 | 59 | 43 | 34 | 57 |
| Avg Precip (In.) | .5 | .52 | .95 | 1.85 | 2.88 | 2.62 | 1.8 | 1.37 | 1.35 | 1.45 | .64 | .59 | 16.52 |