Willsboro, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.7 °C (low) to 13.1 °C (high). Annual precipitation averages 821.2 Millimeters. Willsboro is located in USDA Plant Hardiness Zone 5b. 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 | -11.9 °C | -2.2 °C | 54.61 mm |
| February | -11.1 °C | -0.7 °C | 45.72 mm |
| March | -5.7 °C | 4.1 °C | 59.44 mm |
| April | 1.3 °C | 12.2 °C | 56.39 mm |
| May | 8 °C | 19.6 °C | 69.85 mm |
| June | 13.2 °C | 24.4 °C | 101.09 mm |
| July | 16.1 °C | 27.3 °C | 91.95 mm |
| August | 15.1 °C | 26.3 °C | 79.25 mm |
| September | 10.7 °C | 22.2 °C | 62.99 mm |
| October | 4.5 °C | 14.6 °C | 66.55 mm |
| November | -0.9 °C | 7.8 °C | 68.58 mm |
| December | -7.1 °C | 1.4 °C | 64.77 mm |
| Annual | 2.7 °C | 13.1 °C | 821.19 mm |
| 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 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |