| 2023 Hardiness Zone: | Zone 5a: -20°F to -15°F Zone 4b: -25°F to -20°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.11 - Sep. 20 |
| Average Last Frost Date: | May 21 - May 31 |
| Koppen-Geiger Climate Zone: | Dfb - Humid Continental Mild Summer, Wet All Year |
| Ecoregion: | 43n - Central Grassland |
| Heat Zone Days: | 31 - 45 days Over 86°F |
Annual Climate Data for ZIP Code 59041 - Joliet, MT | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 10 | 15 | 23 | 30 | 39 | 47 | 53 | 51 | 41 | 31 | 20 | 12 | 31 |
| Avg Max Temp (°F) | 34 | 41 | 49 | 58 | 68 | 78 | 85 | 84 | 73 | 61 | 45 | 36 | 59 |
| Avg Precip (In.) | .71 | .61 | 1.22 | 1.89 | 2.9 | 1.73 | 1.09 | 1.06 | 1.4 | 1.5 | .69 | .63 | 15.44 |