West Chatham, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 44.7 °F (low) to 57 °F (high). Annual precipitation averages 45.5 Inches. West Chatham is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 25.5 °F | 38.3 °F | 4.05 in. |
| February | 26.3 °F | 38.9 °F | 3.81 in. |
| March | 31.3 °F | 43.4 °F | 4.57 in. |
| April | 39.7 °F | 51.6 °F | 4.18 in. |
| May | 48.4 °F | 60.7 °F | 3.43 in. |
| June | 57.6 °F | 69.9 °F | 3.15 in. |
| July | 64.6 °F | 76.9 °F | 2.64 in. |
| August | 64.2 °F | 76.6 °F | 3.13 in. |
| September | 58.6 °F | 70.9 °F | 3.68 in. |
| October | 48.7 °F | 60.9 °F | 4.19 in. |
| November | 39.6 °F | 51.9 °F | 3.99 in. |
| December | 31.6 °F | 44.1 °F | 4.65 in. |
| Annual | 44.7 °F | 57 °F | 45.47 in. |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 75-100 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 |