Fort Belknap Agency, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 29.6 °F (low) to 56.6 °F (high). Annual precipitation averages 12.9 Inches. Fort Belknap Agency is located in USDA Plant Hardiness Zone 3b. 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 | 4.9 °F | 27.3 °F | 0.45 in. |
| February | 8.0 °F | 31.7 °F | 0.35 in. |
| March | 18.5 °F | 43.6 °F | 0.49 in. |
| April | 29.8 °F | 57.3 °F | 1.29 in. |
| May | 39.8 °F | 67.5 °F | 2.05 in. |
| June | 48.8 °F | 75.6 °F | 2.71 in. |
| July | 54.2 °F | 85.5 °F | 1.79 in. |
| August | 52.0 °F | 85.0 °F | 1.01 in. |
| September | 42.0 °F | 73.3 °F | 1.19 in. |
| October | 30.4 °F | 58.0 °F | 0.75 in. |
| November | 18.0 °F | 42.8 °F | 0.47 in. |
| December | 8.2 °F | 31.2 °F | 0.35 in. |
| Annual | 29.6 °F | 56.6 °F | 12.9 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 3b : -35°F to -30°F |
| Plant Hardiness Zone - 2012 | Zone 3b : -35°F to -30°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |