Acton, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 0.8 °C (low) to 15.2 °C (high). Annual precipitation averages 394.2 Millimeters. 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 | -9.1 °C | 2.8 °C | 14.22 mm |
| February | -8.6 °C | 4.2 °C | 13.97 mm |
| March | -4.6 °C | 9.3 °C | 23.11 mm |
| April | -0.4 °C | 13.8 °C | 47.24 mm |
| May | 4.6 °C | 18.9 °C | 67.82 mm |
| June | 9.2 °C | 24.2 °C | 61.47 mm |
| July | 12.7 °C | 30 °C | 39.12 mm |
| August | 11.6 °C | 29.6 °C | 24.38 mm |
| September | 6.8 °C | 23.5 °C | 35.05 mm |
| October | 0.8 °C | 15.4 °C | 37.85 mm |
| November | -4.7 °C | 8.1 °C | 15.24 mm |
| December | -8.7 °C | 2.8 °C | 14.73 mm |
| Annual | 0.8 °C | 15.2 °C | 394.2 mm |
| 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 : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |