Fort Belknap Agency, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from -1.4 °C (low) to 13.6 °C (high). Annual precipitation averages 327.7 Millimeters. 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 | -15.1 °C | -2.6 °C | 11.43 mm |
| February | -13.3 °C | -0.2 °C | 8.89 mm |
| March | -7.5 °C | 6.4 °C | 12.45 mm |
| April | -1.2 °C | 14.1 °C | 32.77 mm |
| May | 4.3 °C | 19.7 °C | 52.07 mm |
| June | 9.3 °C | 24.2 °C | 68.83 mm |
| July | 12.3 °C | 29.7 °C | 45.47 mm |
| August | 11.1 °C | 29.4 °C | 25.65 mm |
| September | 5.6 °C | 22.9 °C | 30.23 mm |
| October | -0.9 °C | 14.4 °C | 19.05 mm |
| November | -7.8 °C | 6 °C | 11.94 mm |
| December | -13.2 °C | -0.4 °C | 8.89 mm |
| Annual | -1.4 °C | 13.6 °C | 327.67 mm |
| 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 : -37.2°C to -34.4°C |
| Plant Hardiness Zone - 2012 | Zone 3b : -37.2°C to -34.4°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |