Londonderry, Vermont has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.1 °C (low) to 12.2 °C (high). Annual precipitation averages 1221.8 Millimeters. Londonderry 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 | -12.7 °C | -1.8 °C | 92.46 mm |
| February | -12.7 °C | -0.4 °C | 76.71 mm |
| March | -7.9 °C | 4.1 °C | 96.77 mm |
| April | -1.3 °C | 11.2 °C | 96.01 mm |
| May | 5.4 °C | 18.3 °C | 96.77 mm |
| June | 10.3 °C | 22.8 °C | 115.32 mm |
| July | 12.7 °C | 25.5 °C | 107.7 mm |
| August | 11.7 °C | 24.6 °C | 106.43 mm |
| September | 7.2 °C | 20.9 °C | 99.82 mm |
| October | 1.4 °C | 13.6 °C | 129.54 mm |
| November | -3.7 °C | 7.1 °C | 100.33 mm |
| December | -8.7 °C | 0.9 °C | 103.89 mm |
| Annual | 0.1 °C | 12.2 °C | 1221.75 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 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |