Williamstown, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 36 °F (low) to 55.6 °F (high). Annual precipitation averages 53.5 Inches. Williamstown is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 12.1 °F | 29.2 °F | 4.91 in. |
| February | 13.2 °F | 31.4 °F | 4.12 in. |
| March | 21.1 °F | 39.7 °F | 3.98 in. |
| April | 33.0 °F | 54.1 °F | 3.94 in. |
| May | 44.5 °F | 67.3 °F | 4.3 in. |
| June | 53.7 °F | 75.3 °F | 4.15 in. |
| July | 58.4 °F | 79.7 °F | 4.19 in. |
| August | 56.8 °F | 78.6 °F | 4.28 in. |
| September | 49.6 °F | 71.8 °F | 4.47 in. |
| October | 39.6 °F | 58.6 °F | 5.46 in. |
| November | 30.2 °F | 46.1 °F | 4.6 in. |
| December | 20.3 °F | 35.0 °F | 5.06 in. |
| Annual | 36 °F | 55.6 °F | 53.46 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°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 |