| 2023 Hardiness Zone: | Zone 3b: -35°F to -30°F Zone 4a: -30°F to -25°F | |
| 2012 Hardiness Zone: | Zone 4a: -30°F to -25°F | |
| 1990 Hardiness Zone: | Zone 3b: -35F to -30F | |
| Average First Frost Date: | Sep.11 - Sep. 20 | |
| Average Last Frost Date: | May 21 - May 31 | |
| Koppen-Geiger Climate Zone: | BSk - Cold Semi-Arid Climate | |
| Ecoregion: | 42o - North Central Brown Glaciated Plains | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 59474 - Shelby, MT | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 7 | 13 | 21 | 30 | 39 | 47 | 51 | 50 | 40 | 31 | 19 | 10 | 30 |
| Avg Max Temp (°F) | 29 | 36 | 45 | 57 | 67 | 75 | 82 | 82 | 71 | 59 | 40 | 31 | 56 |
| Avg Precip (In.) | .36 | .27 | .57 | .95 | 2.04 | 2.3 | 1.43 | 1.57 | 1.04 | .58 | .39 | .33 | 11.83 |