Acton, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.6 °C (low) to 15.4 °C (high). Annual precipitation averages 1238.8 Millimeters. Acton is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.1 °C | 1.6 °C | 93.22 mm |
| February | -8.1 °C | 3.1 °C | 86.61 mm |
| March | -3.7 °C | 7.3 °C | 112.52 mm |
| April | 2.1 °C | 14.6 °C | 109.73 mm |
| May | 7.8 °C | 20.4 °C | 95.5 mm |
| June | 13.1 °C | 25.2 °C | 111.51 mm |
| July | 16.2 °C | 28.6 °C | 94.23 mm |
| August | 15.4 °C | 27.7 °C | 97.79 mm |
| September | 10.8 °C | 23.8 °C | 97.54 mm |
| October | 4.4 °C | 17 °C | 123.7 mm |
| November | -0.8 °C | 10.7 °C | 97.03 mm |
| December | -5.4 °C | 4.8 °C | 119.38 mm |
| Annual | 3.6 °C | 15.4 °C | 1238.76 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |