Dover, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.7 °C (low) to 14.4 °C (high). Annual precipitation averages 1150.9 Millimeters. Dover 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 | -9.8 °C | 0.7 °C | 77.72 mm |
| February | -8.8 °C | 2.2 °C | 78.99 mm |
| March | -4.5 °C | 6.4 °C | 97.28 mm |
| April | 1.1 °C | 13.3 °C | 105.41 mm |
| May | 6.7 °C | 19.2 °C | 92.46 mm |
| June | 11.8 °C | 24.4 °C | 103.38 mm |
| July | 15.2 °C | 27.6 °C | 97.03 mm |
| August | 14.2 °C | 27.1 °C | 88.65 mm |
| September | 9.9 °C | 22.9 °C | 92.71 mm |
| October | 3.6 °C | 16 °C | 115.32 mm |
| November | -1.2 °C | 9.6 °C | 96.01 mm |
| December | -6 °C | 3.5 °C | 105.92 mm |
| Annual | 2.7 °C | 14.4 °C | 1150.88 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 |