| 2023 Hardiness Zone: | Zone 4b: -25°F to -20°F | |
| 2012 Hardiness Zone: | 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: | 42o - North Central Brown Glaciated Plains | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | 1 - 7 days Over 86°F |
Annual Climate Data for ZIP Code 59401 - Great Falls, MT | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 12 | 16 | 23 | 31 | 39 | 47 | 51 | 51 | 42 | 34 | 23 | 15 | 32 |
| Avg Max Temp (°F) | 32 | 38 | 46 | 56 | 65 | 74 | 82 | 81 | 70 | 58 | 42 | 34 | 57 |
| Avg Precip (In.) | .66 | .5 | .99 | 1.39 | 2.51 | 2.25 | 1.41 | 1.64 | 1.22 | .92 | .59 | .66 | 14.74 |