| 2023 Hardiness Zone: | Zone 5a: -20°F to -15°F Zone 4b: -25°F to -20°F Zone 4a: -30°F to -25°F |
| 2012 Hardiness Zone: | Zone 5a: -20°F to -15°F Zone 5b: -15°F to -10°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: | Dfb - Humid Continental Mild Summer, Wet All Year |
| Ecoregion: | 43n - Central Grassland |
| Heat Zone Days: | 61 - 90 days Over 86°F |
Annual Climate Data for ZIP Code 59034 - Hardin, MT | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 10 | 15 | 24 | 33 | 42 | 50 | 55 | 54 | 43 | 33 | 21 | 12 | 33 |
| Avg Max Temp (°F) | 35 | 42 | 52 | 62 | 73 | 82 | 90 | 90 | 78 | 65 | 47 | 37 | 63 |
| Avg Precip (In.) | .62 | .37 | .69 | 1.4 | 2 | 1.7 | 1.14 | .67 | 1.31 | 1.29 | .62 | .48 | 12.29 |