Litchfield, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.9 °C (low) to 15.2 °C (high). Annual precipitation averages 1175.3 Millimeters. Litchfield 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -10.1 °C | 1.1 °C | 83.82 mm |
| February | -9.2 °C | 2.7 °C | 81.03 mm |
| March | -4.6 °C | 7.1 °C | 102.62 mm |
| April | 1.4 °C | 14.4 °C | 101.35 mm |
| May | 7.5 °C | 20.6 °C | 93.98 mm |
| June | 12.7 °C | 25.6 °C | 105.92 mm |
| July | 15.8 °C | 28.6 °C | 90.93 mm |
| August | 14.8 °C | 27.7 °C | 94.74 mm |
| September | 10.4 °C | 23.6 °C | 96.27 mm |
| October | 3.7 °C | 16.4 °C | 120.4 mm |
| November | -1.4 °C | 9.9 °C | 95.76 mm |
| December | -6.3 °C | 4.1 °C | 108.46 mm |
| Annual | 2.9 °C | 15.2 °C | 1175.28 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| 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 | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |