| 2023 Hardiness Zone: | Zone 3b: -35°F to -30°F Zone 4b: -25°F to -20°F Zone 5a: -20°F to -15°F Zone 4a: -30°F to -25°F |
| 2012 Hardiness Zone: | Zone 3b: -35°F to -30°F Zone 4b: -25°F to -20°F Zone 5a: -20°F to -15°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: | 43t - Shield-Smith Valleys |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 59645 - White Sulphur Springs, MT | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 10 | 16 | 19 | 27 | 35 | 42 | 47 | 46 | 37 | 29 | 21 | 13 | 28 |
| Avg Max Temp (°F) | 30 | 37 | 42 | 51 | 60 | 70 | 78 | 78 | 67 | 56 | 40 | 33 | 53 |
| Avg Precip (In.) | .84 | .86 | .75 | 1.13 | 2.3 | 2.13 | 1.62 | 1.4 | 1.28 | .79 | .61 | .86 | 14.59 |