Williston, Vermont has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 34.4 °F (low) to 54.2 °F (high). Annual precipitation averages 43 Inches. Williston is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 8.5 °F | 27.4 °F | 2.53 in. |
| February | 9.5 °F | 30.1 °F | 2.09 in. |
| March | 18.9 °F | 38.7 °F | 2.76 in. |
| April | 32.0 °F | 52.4 °F | 3.53 in. |
| May | 43.8 °F | 66.1 °F | 3.91 in. |
| June | 53.3 °F | 74.6 °F | 4.61 in. |
| July | 58.4 °F | 79.2 °F | 4.76 in. |
| August | 56.6 °F | 77.4 °F | 4.28 in. |
| September | 48.7 °F | 69.9 °F | 4.0 in. |
| October | 37.7 °F | 56.5 °F | 4.3 in. |
| November | 28.1 °F | 44.8 °F | 3.15 in. |
| December | 17.0 °F | 33.3 °F | 3.09 in. |
| Annual | 34.4 °F | 54.2 °F | 43.01 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 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 |