Wilton, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.6 °C (low) to 14.6 °C (high). Annual precipitation averages 1237.7 Millimeters. Wilton is located in USDA Plant Hardiness Zone 6a. 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 | -10.1 °C | 0.4 °C | 89.15 mm |
| February | -9.3 °C | 2.2 °C | 85.09 mm |
| March | -4.8 °C | 6.6 °C | 103.12 mm |
| April | 1.2 °C | 13.9 °C | 104.14 mm |
| May | 7.1 °C | 20.1 °C | 98.55 mm |
| June | 12.3 °C | 25.1 °C | 109.73 mm |
| July | 15.3 °C | 28 °C | 101.09 mm |
| August | 14.2 °C | 27.1 °C | 99.82 mm |
| September | 9.9 °C | 23 °C | 104.39 mm |
| October | 3.6 °C | 15.8 °C | 128.78 mm |
| November | -1.6 °C | 9.6 °C | 100.84 mm |
| December | -6.5 °C | 3.4 °C | 113.03 mm |
| Annual | 2.6 °C | 14.6 °C | 1237.73 mm |
| 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 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |