| 2023 Hardiness Zone: | Zone 5a: -20°F to -15°F Zone 6b: -5°F to 0°F Zone 4b: -25°F to -20°F Zone 6a: -10°F to -5°F Zone 5b: -15°F to -10°F | |
| 2012 Hardiness Zone: | Zone 5a: -20°F to -15°F Zone 6b: -5°F to 0°F Zone 4b: -25°F to -20°F Zone 6a: -10°F to -5°F Zone 5b: -15°F to -10°F | |
| 1990 Hardiness Zone: | Zone 1b: -15F to -10F | |
| Average First Frost Date: | Sep.11 - Sep. 20 | |
| Average Last Frost Date: | Jun. 21 - Jun. 30 | |
| Koppen-Geiger Climate Zone: | Dfb - Humid Continental Mild Summer, Wet All Year | |
| Ecoregion: | 15a - Grave Creek Range-Nine Mile Divide | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | 15 - 30 days Over 86°F |
Annual Climate Data for ZIP Code 59859 - Plains, MT | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 17 | 20 | 26 | 32 | 39 | 45 | 49 | 48 | 40 | 31 | 24 | 18 | 32 |
| Avg Max Temp (°F) | 33 | 39 | 49 | 59 | 67 | 75 | 84 | 84 | 73 | 58 | 41 | 33 | 58 |
| Avg Precip (In.) | 1.3 | 1.05 | 1.12 | 1.36 | 1.97 | 1.93 | 1.06 | 1.28 | 1.32 | 1.31 | 1.36 | 1.37 | 16.42 |