Williamsburg, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 35.5 °F (low) to 57.3 °F (high). Annual precipitation averages 51.4 Inches. Williamsburg is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 12.1 °F | 31.7 °F | 3.6 in. |
| February | 13.4 °F | 34.7 °F | 3.34 in. |
| March | 22.0 °F | 43.0 °F | 4.11 in. |
| April | 33.0 °F | 56.2 °F | 4.2 in. |
| May | 44.0 °F | 67.8 °F | 4.04 in. |
| June | 53.2 °F | 76.3 °F | 4.77 in. |
| July | 58.5 °F | 81.4 °F | 4.37 in. |
| August | 56.5 °F | 79.5 °F | 4.42 in. |
| September | 48.8 °F | 72.5 °F | 4.87 in. |
| October | 37.7 °F | 59.7 °F | 5.24 in. |
| November | 27.9 °F | 47.9 °F | 3.98 in. |
| December | 19.0 °F | 37.0 °F | 4.5 in. |
| Annual | 35.5 °F | 57.3 °F | 51.44 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |