Durham, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.8 °C (low) to 14.4 °C (high). Annual precipitation averages 1146.6 Millimeters. Durham 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 | -9.6 °C | 0.8 °C | 75.44 mm |
| February | -8.7 °C | 2.3 °C | 77.22 mm |
| March | -4.4 °C | 6.4 °C | 94.23 mm |
| April | 1.2 °C | 13.3 °C | 104.14 mm |
| May | 6.7 °C | 19.2 °C | 92.46 mm |
| June | 11.9 °C | 24.4 °C | 102.87 mm |
| July | 15.2 °C | 27.5 °C | 98.81 mm |
| August | 14.3 °C | 27.1 °C | 91.19 mm |
| September | 10 °C | 22.9 °C | 96.77 mm |
| October | 3.7 °C | 16.1 °C | 112.78 mm |
| November | -1.2 °C | 9.7 °C | 96.52 mm |
| December | -5.9 °C | 3.6 °C | 104.14 mm |
| Annual | 2.8 °C | 14.4 °C | 1146.57 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 |