Simms, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 32.4 °F (low) to 58.1 °F (high). Annual precipitation averages 12.2 Inches. Simms 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 | 14.9 °F | 36.6 °F | 0.34 in. |
| February | 16.0 °F | 38.9 °F | 0.35 in. |
| March | 22.4 °F | 46.8 °F | 0.56 in. |
| April | 30.6 °F | 55.9 °F | 1.51 in. |
| May | 39.1 °F | 65.1 °F | 1.86 in. |
| June | 46.6 °F | 73.0 °F | 2.54 in. |
| July | 51.7 °F | 83.8 °F | 1.09 in. |
| August | 50.1 °F | 82.9 °F | 1.09 in. |
| September | 42.7 °F | 72.5 °F | 1.18 in. |
| October | 33.6 °F | 58.8 °F | 0.77 in. |
| November | 24.2 °F | 45.3 °F | 0.48 in. |
| December | 16.4 °F | 37.0 °F | 0.42 in. |
| Annual | 32.4 °F | 58.1 °F | 12.19 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 | Moderate Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |