Westwood, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 40.5 °F (low) to 60 °F (high). Annual precipitation averages 49.7 Inches. Westwood 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 18.4 °F | 36.4 °F | 4.03 in. |
| February | 20.0 °F | 38.9 °F | 3.46 in. |
| March | 27.3 °F | 46.0 °F | 4.87 in. |
| April | 37.5 °F | 58.0 °F | 4.44 in. |
| May | 47.3 °F | 68.4 °F | 3.6 in. |
| June | 56.7 °F | 77.1 °F | 4.12 in. |
| July | 62.7 °F | 82.9 °F | 3.59 in. |
| August | 61.2 °F | 81.5 °F | 3.88 in. |
| September | 54.0 °F | 74.5 °F | 3.79 in. |
| October | 42.5 °F | 62.5 °F | 4.93 in. |
| November | 33.2 °F | 51.9 °F | 4.16 in. |
| December | 24.7 °F | 41.9 °F | 4.87 in. |
| Annual | 40.5 °F | 60 °F | 49.74 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |