| 2023 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 5a: -20°F to -15°F Zone 5b: -15°F to -10°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 6a: -10°F to -5°F Zone 4a: -30°F to -25°F | |
| 1990 Hardiness Zone: | Zone 4a: -30F to -25F | |
| Average First Frost Date: | Aug. 21 - Aug. 31 | |
| Average Last Frost Date: | Jun. 11 - Jun. 20 | |
| Koppen-Geiger Climate Zone: | Dfb - Humid Continental Mild Summer, Wet All Year | |
| Ecoregion: | 17s - Bitterroot-Frenchtown Valley | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | 1 - 7 days Over 86°F |
Annual Climate Data for ZIP Code 59829 - Darby, MT | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 18 | 21 | 26 | 31 | 39 | 44 | 48 | 47 | 40 | 33 | 24 | 18 | 32 |
| Avg Max Temp (°F) | 35 | 41 | 50 | 58 | 66 | 74 | 82 | 82 | 72 | 60 | 43 | 35 | 58 |
| Avg Precip (In.) | 1.45 | 1.06 | .95 | 1.14 | 1.97 | 1.99 | 1.08 | 1.24 | 1.12 | 1.04 | 1.45 | 1.48 | 15.97 |