Fort Benton, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 31.4 °F (low) to 59.6 °F (high). Annual precipitation averages 13.3 Inches. Fort Benton is located in USDA Plant Hardiness Zone 4a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 10.1 °F | 35.0 °F | 0.51 in. |
| February | 12.5 °F | 39.0 °F | 0.44 in. |
| March | 20.7 °F | 47.9 °F | 0.52 in. |
| April | 31.4 °F | 59.1 °F | 1.49 in. |
| May | 40.6 °F | 67.5 °F | 2.13 in. |
| June | 48.8 °F | 76.0 °F | 2.58 in. |
| July | 54.0 °F | 86.1 °F | 1.25 in. |
| August | 51.7 °F | 85.6 °F | 1.19 in. |
| September | 42.6 °F | 75.0 °F | 1.18 in. |
| October | 30.8 °F | 60.4 °F | 0.92 in. |
| November | 20.9 °F | 46.5 °F | 0.59 in. |
| December | 12.7 °F | 36.6 °F | 0.48 in. |
| Annual | 31.4 °F | 59.6 °F | 13.28 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4a : -30°F to -25°F |
| Plant Hardiness Zone - 2012 | Zone 4a : -30°F to -25°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |