Chilmark, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 45.8 °F (low) to 57.8 °F (high). Annual precipitation averages 48.1 Inches. 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 | 26.7 °F | 39.4 °F | 4.17 in. |
| February | 27.2 °F | 39.7 °F | 3.66 in. |
| March | 32.0 °F | 43.9 °F | 5.1 in. |
| April | 40.5 °F | 52.8 °F | 4.36 in. |
| May | 49.1 °F | 61.8 °F | 3.48 in. |
| June | 58.3 °F | 70.4 °F | 3.5 in. |
| July | 65.3 °F | 77.0 °F | 2.82 in. |
| August | 65.5 °F | 76.9 °F | 3.47 in. |
| September | 60.1 °F | 71.6 °F | 3.81 in. |
| October | 50.7 °F | 62.3 °F | 4.68 in. |
| November | 41.2 °F | 53.2 °F | 4.14 in. |
| December | 32.8 °F | 45.1 °F | 4.91 in. |
| Annual | 45.8 °F | 57.8 °F | 48.1 in. |
| 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 : 5°F to 10°F |
| Plant Hardiness Zone - 2012 | Zone 7a : 0°F to 5°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |