Belfry, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 31.5 °F (low) to 60.1 °F (high). Annual precipitation averages 10.2 Inches. Belfry is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 11.3 °F | 36.8 °F | 0.32 in. |
| February | 14.1 °F | 39.8 °F | 0.3 in. |
| March | 22.9 °F | 50.9 °F | 0.52 in. |
| April | 30.6 °F | 58.4 °F | 0.95 in. |
| May | 40.0 °F | 67.3 °F | 1.91 in. |
| June | 48.1 °F | 77.5 °F | 1.82 in. |
| July | 54.0 °F | 86.9 °F | 0.86 in. |
| August | 51.4 °F | 85.7 °F | 0.66 in. |
| September | 42.4 °F | 74.7 °F | 1.0 in. |
| October | 30.8 °F | 60.2 °F | 0.96 in. |
| November | 20.9 °F | 46.6 °F | 0.46 in. |
| December | 11.8 °F | 36.8 °F | 0.39 in. |
| Annual | 31.5 °F | 60.1 °F | 10.15 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 4b : -25°F to -20°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |