| 2023 Hardiness Zone: | Zone 5a: -20°F to -15°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 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: | Aug. 21 - Aug. 31 | |
| Average Last Frost Date: | Jun. 21 - Jun. 30 | |
| Koppen-Geiger Climate Zone: | Dfb - Humid Continental Mild Summer, Wet All Year | |
| Ecoregion: | 15d - Tobacco Plains | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | 15 - 30 days Over 86°F |
Annual Climate Data for ZIP Code 59917 - Eureka, MT | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 14 | 19 | 26 | 32 | 39 | 45 | 49 | 48 | 39 | 31 | 25 | 17 | 32 |
| Avg Max Temp (°F) | 29 | 37 | 48 | 58 | 67 | 74 | 83 | 83 | 71 | 57 | 39 | 30 | 56 |
| Avg Precip (In.) | 1.1 | .79 | .78 | .91 | 1.81 | 2.02 | 1.47 | 1.22 | 1.04 | .97 | 1.21 | 1.12 | 14.44 |