Belknap, Montana has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 34.8 °F (low) to 59.4 °F (high). Annual precipitation averages 22.7 Inches. Belknap is located in USDA Plant Hardiness Zone 6b. 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 | 22.6 °F | 35.2 °F | 2.45 in. |
| February | 23.3 °F | 40.6 °F | 1.98 in. |
| March | 27.5 °F | 49.2 °F | 2.05 in. |
| April | 32.7 °F | 58.5 °F | 1.69 in. |
| May | 39.3 °F | 68.9 °F | 2.11 in. |
| June | 45.8 °F | 75.2 °F | 2.25 in. |
| July | 49.9 °F | 86.5 °F | 0.91 in. |
| August | 48.9 °F | 87.0 °F | 0.82 in. |
| September | 42.1 °F | 76.0 °F | 0.97 in. |
| October | 34.4 °F | 58.9 °F | 2.13 in. |
| November | 28.2 °F | 42.5 °F | 2.79 in. |
| December | 22.9 °F | 34.4 °F | 2.59 in. |
| Annual | 34.8 °F | 59.4 °F | 22.74 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |