Great Falls, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 33.9 °F (low) to 58.3 °F (high). Annual precipitation averages 14.6 Inches. Great Falls is located in USDA Plant Hardiness Zone 4b. 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 | 15.9 °F | 36.2 °F | 0.61 in. |
| February | 16.6 °F | 38.3 °F | 0.57 in. |
| March | 23.5 °F | 46.8 °F | 0.66 in. |
| April | 32.0 °F | 56.0 °F | 1.68 in. |
| May | 40.9 °F | 65.5 °F | 2.19 in. |
| June | 48.5 °F | 73.7 °F | 2.71 in. |
| July | 54.1 °F | 84.7 °F | 1.21 in. |
| August | 52.7 °F | 84.1 °F | 1.11 in. |
| September | 44.7 °F | 73.0 °F | 1.3 in. |
| October | 34.4 °F | 58.8 °F | 1.14 in. |
| November | 25.3 °F | 45.8 °F | 0.79 in. |
| December | 17.7 °F | 37.0 °F | 0.59 in. |
| Annual | 33.9 °F | 58.3 °F | 14.56 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 4b : -25°F to -20°F |
| Plant Hardiness Zone - 2012 | Zone 4a : -30°F to -25°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |