Acton, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 33.4 °F (low) to 59.4 °F (high). Annual precipitation averages 15.5 Inches. Acton is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 15.6 °F | 37.1 °F | 0.56 in. |
| February | 16.6 °F | 39.5 °F | 0.55 in. |
| March | 23.7 °F | 48.7 °F | 0.91 in. |
| April | 31.2 °F | 56.8 °F | 1.86 in. |
| May | 40.3 °F | 66.1 °F | 2.67 in. |
| June | 48.6 °F | 75.6 °F | 2.42 in. |
| July | 54.9 °F | 86.0 °F | 1.54 in. |
| August | 52.9 °F | 85.2 °F | 0.96 in. |
| September | 44.2 °F | 74.3 °F | 1.38 in. |
| October | 33.4 °F | 59.7 °F | 1.49 in. |
| November | 23.6 °F | 46.6 °F | 0.6 in. |
| December | 16.3 °F | 37.1 °F | 0.58 in. |
| Annual | 33.4 °F | 59.4 °F | 15.52 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |