Williamson, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 40 °F (low) to 57.6 °F (high). Annual precipitation averages 38.5 Inches. Williamson 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 | 18.0 °F | 33.1 °F | 2.88 in. |
| February | 19.3 °F | 34.1 °F | 2.28 in. |
| March | 25.5 °F | 42.7 °F | 2.66 in. |
| April | 35.9 °F | 55.6 °F | 3.08 in. |
| May | 46.7 °F | 68.0 °F | 3.19 in. |
| June | 56.3 °F | 75.4 °F | 3.45 in. |
| July | 62.0 °F | 81.1 °F | 3.57 in. |
| August | 60.7 °F | 79.8 °F | 3.55 in. |
| September | 53.9 °F | 73.7 °F | 3.39 in. |
| October | 43.1 °F | 60.4 °F | 3.95 in. |
| November | 33.4 °F | 49.0 °F | 3.31 in. |
| December | 24.6 °F | 38.0 °F | 3.14 in. |
| Annual | 40 °F | 57.6 °F | 38.45 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |