Fort Peck, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from -0.4 °C (low) to 14.1 °C (high). Annual precipitation averages 341.1 Millimeters. Fort Peck is located in USDA Plant Hardiness Zone 4a. 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 | -15.3 °C | -3.1 °C | 9.91 mm |
| February | -13 °C | -0.1 °C | 9.4 mm |
| March | -6.7 °C | 6.8 °C | 12.45 mm |
| April | -0.5 °C | 14.7 °C | 25.15 mm |
| May | 5.4 °C | 20.6 °C | 59.69 mm |
| June | 10.8 °C | 25.6 °C | 65.28 mm |
| July | 13.8 °C | 30.6 °C | 47.5 mm |
| August | 12.8 °C | 30.4 °C | 34.8 mm |
| September | 7.1 °C | 24.2 °C | 28.96 mm |
| October | 0.3 °C | 15.1 °C | 24.89 mm |
| November | -6.9 °C | 6 °C | 11.68 mm |
| December | -13 °C | -1.2 °C | 11.43 mm |
| Annual | -0.4 °C | 14.1 °C | 341.14 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 4a : -34.4°C to -31.7°C |
| Plant Hardiness Zone - 2012 | Zone 4a : -34.4°C to -31.7°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |