Chilmark, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 7.7 °C (low) to 14.4 °C (high). Annual precipitation averages 1221.7 Millimeters. Chilmark is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -2.9 °C | 4.1 °C | 105.92 mm |
| February | -2.7 °C | 4.3 °C | 92.96 mm |
| March | 0 °C | 6.6 °C | 129.54 mm |
| April | 4.7 °C | 11.6 °C | 110.74 mm |
| May | 9.5 °C | 16.6 °C | 88.39 mm |
| June | 14.6 °C | 21.3 °C | 88.9 mm |
| July | 18.5 °C | 25 °C | 71.63 mm |
| August | 18.6 °C | 24.9 °C | 88.14 mm |
| September | 15.6 °C | 22 °C | 96.77 mm |
| October | 10.4 °C | 16.8 °C | 118.87 mm |
| November | 5.1 °C | 11.8 °C | 105.16 mm |
| December | 0.4 °C | 7.3 °C | 124.71 mm |
| Annual | 7.7 °C | 14.4 °C | 1221.73 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7b : -15°C to -12.2°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |