Deerfield, 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 14.4 °C (high). Annual precipitation averages 1194.8 Millimeters. Deerfield is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.5 °C | 0.1 °C | 81.79 mm |
| February | -8.9 °C | 1.8 °C | 79.5 mm |
| March | -4.3 °C | 6.1 °C | 97.79 mm |
| April | 1.3 °C | 13.6 °C | 96.77 mm |
| May | 7.2 °C | 19.8 °C | 101.6 mm |
| June | 12.8 °C | 24.9 °C | 116.08 mm |
| July | 15.6 °C | 27.8 °C | 97.54 mm |
| August | 14.9 °C | 27 °C | 99.82 mm |
| September | 10.4 °C | 23 °C | 97.03 mm |
| October | 4.6 °C | 15.8 °C | 122.94 mm |
| November | -1 °C | 9.2 °C | 95 mm |
| December | -6.1 °C | 3.2 °C | 108.97 mm |
| Annual | 3.1 °C | 14.4 °C | 1194.83 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 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 |