Wilton, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.7 °C (low) to 12.1 °C (high). Annual precipitation averages 1238.5 Millimeters. Wilton is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -13.5 °C | -2.9 °C | 87.63 mm |
| February | -12.8 °C | -1.2 °C | 76.96 mm |
| March | -7.2 °C | 3.6 °C | 94.74 mm |
| April | -0.6 °C | 11 °C | 104.9 mm |
| May | 5.5 °C | 18.3 °C | 97.79 mm |
| June | 10.8 °C | 22.9 °C | 128.02 mm |
| July | 13.8 °C | 25.8 °C | 101.6 mm |
| August | 12.7 °C | 25.3 °C | 99.06 mm |
| September | 8.3 °C | 21.2 °C | 89.66 mm |
| October | 2.6 °C | 13.7 °C | 140.21 mm |
| November | -2.8 °C | 6.6 °C | 108.71 mm |
| December | -8.7 °C | 0.4 °C | 109.22 mm |
| Annual | 0.7 °C | 12.1 °C | 1238.5 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |