Westford, Vermont has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 35.5 °F (low) to 54.5 °F (high). Annual precipitation averages 43 Inches. Westford is located in USDA Plant Hardiness Zone 5a. 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 | 8.5 °F | 26.8 °F | 2.63 in. |
| February | 10.0 °F | 29.7 °F | 2.13 in. |
| March | 19.8 °F | 38.7 °F | 2.76 in. |
| April | 33.1 °F | 53.0 °F | 3.46 in. |
| May | 45.2 °F | 66.8 °F | 3.99 in. |
| June | 54.8 °F | 75.1 °F | 4.51 in. |
| July | 59.9 °F | 79.6 °F | 4.59 in. |
| August | 58.1 °F | 78.5 °F | 4.29 in. |
| September | 50.4 °F | 70.8 °F | 4.04 in. |
| October | 39.3 °F | 57.2 °F | 4.25 in. |
| November | 29.2 °F | 44.7 °F | 3.13 in. |
| December | 17.6 °F | 33.1 °F | 3.17 in. |
| Annual | 35.5 °F | 54.5 °F | 42.95 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |