Heart Butte, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from -1 °C (low) to 11.4 °C (high). Annual precipitation averages 446.5 Millimeters. Heart Butte is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Sep.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.8 °C | 0.8 °C | 20.57 mm |
| February | -9.5 °C | 1.4 °C | 23.88 mm |
| March | -6.3 °C | 5 °C | 26.16 mm |
| April | -2.2 °C | 9.4 °C | 41.91 mm |
| May | 2.2 °C | 14.8 °C | 60.96 mm |
| June | 6 °C | 19.1 °C | 84.58 mm |
| July | 9.1 °C | 25.1 °C | 36.07 mm |
| August | 8.4 °C | 24.8 °C | 32 mm |
| September | 4.4 °C | 18.9 °C | 37.34 mm |
| October | -0.4 °C | 11.6 °C | 33.78 mm |
| November | -4.7 °C | 4.9 °C | 27.94 mm |
| December | -8.6 °C | 0.9 °C | 21.34 mm |
| Annual | -1 °C | 11.4 °C | 446.53 mm |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 4b : -31.7°C to -28.9°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 |