Nashua, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.1 °C (low) to 15.3 °C (high). Annual precipitation averages 1199.6 Millimeters. Nashua is located in USDA Plant Hardiness Zone 6a. 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 | -9.8 °C | 1.2 °C | 86.11 mm |
| February | -8.8 °C | 2.8 °C | 82.55 mm |
| March | -4.3 °C | 7.2 °C | 106.93 mm |
| April | 1.6 °C | 14.5 °C | 103.38 mm |
| May | 7.6 °C | 20.6 °C | 96.52 mm |
| June | 12.8 °C | 25.7 °C | 108.97 mm |
| July | 15.9 °C | 28.7 °C | 91.95 mm |
| August | 14.9 °C | 27.8 °C | 98.04 mm |
| September | 10.6 °C | 23.7 °C | 96.77 mm |
| October | 3.9 °C | 16.6 °C | 122.43 mm |
| November | -1.2 °C | 10.1 °C | 96.52 mm |
| December | -6.1 °C | 4.2 °C | 109.47 mm |
| Annual | 3.1 °C | 15.3 °C | 1199.64 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 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 |