| 2023 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 6b: -5°F to 0°F Zone 5b: -15°F to -10°F | |
| 2012 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 5a: -20°F to -15°F Zone 5b: -15°F to -10°F | |
| 1990 Hardiness Zone: | Zone 4b: -25F to -20F | |
| Average First Frost Date: | Sep. 21 - Sep. 30 | |
| Average Last Frost Date: | Jun. 1 - Jun. 10 | |
| Koppen-Geiger Climate Zone: | Dfb - Humid Continental Mild Summer, Wet All Year | |
| Ecoregion: | 15c - Flathead Valley | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 59860 - Polson, MT | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 19 | 23 | 28 | 34 | 41 | 48 | 52 | 52 | 44 | 35 | 27 | 21 | 35 |
| Avg Max Temp (°F) | 33 | 38 | 47 | 57 | 66 | 74 | 82 | 82 | 70 | 57 | 41 | 33 | 57 |
| Avg Precip (In.) | 1.07 | .84 | 1.09 | 1.31 | 2.32 | 2.33 | 1.36 | 1.36 | 1.32 | 1.15 | 1.16 | 1.2 | 16.5 |