| 2023 Hardiness Zone: | Zone 4b: -25°F to -20°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: | Jun. 1 - Jun. 10 | |
| 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 59484 - Sweet Grass, MT | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 8 | 14 | 22 | 31 | 41 | 48 | 52 | 52 | 42 | 33 | 20 | 11 | 31 |
| Avg Max Temp (°F) | 30 | 37 | 45 | 57 | 67 | 75 | 81 | 81 | 71 | 59 | 42 | 32 | 56 |
| Avg Precip (In.) | .31 | .23 | .58 | .99 | 2.58 | 3.03 | 1.86 | 1.9 | 1.4 | .61 | .44 | .31 | 14.26 |