Londonderry, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.3 °C (low) to 14.6 °C (high). Annual precipitation averages 1188.7 Millimeters. Londonderry 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 | -9.2 °C | 0.8 °C | 82.3 mm |
| February | -8.3 °C | 2.2 °C | 82.04 mm |
| March | -4.2 °C | 6.6 °C | 102.62 mm |
| April | 1.9 °C | 13.8 °C | 101.09 mm |
| May | 7.4 °C | 19.9 °C | 95.5 mm |
| June | 12.7 °C | 24.8 °C | 107.95 mm |
| July | 15.7 °C | 27.8 °C | 93.47 mm |
| August | 14.6 °C | 27.1 °C | 95.5 mm |
| September | 10.6 °C | 23.1 °C | 99.82 mm |
| October | 4.4 °C | 15.8 °C | 121.92 mm |
| November | -0.5 °C | 9.8 °C | 97.54 mm |
| December | -5.8 °C | 3.6 °C | 108.97 mm |
| Annual | 3.3 °C | 14.6 °C | 1188.72 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 | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |