Chesterfield, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.1 °C (low) to 13.4 °C (high). Annual precipitation averages 1236.5 Millimeters. Chesterfield 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 Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -10.6 °C | -0.8 °C | 88.14 mm |
| February | -9.8 °C | 0.8 °C | 77.72 mm |
| March | -5.6 °C | 5.2 °C | 91.95 mm |
| April | 0.6 °C | 12.7 °C | 95.25 mm |
| May | 6.4 °C | 19.3 °C | 99.06 mm |
| June | 11.9 °C | 24 °C | 115.57 mm |
| July | 15.1 °C | 26.8 °C | 112.78 mm |
| August | 13.4 °C | 26 °C | 112.78 mm |
| September | 9.4 °C | 21.9 °C | 108.71 mm |
| October | 3.3 °C | 14.8 °C | 129.29 mm |
| November | -1.7 °C | 8.3 °C | 94.74 mm |
| December | -6.9 °C | 2.3 °C | 110.49 mm |
| Annual | 2.1 °C | 13.4 °C | 1236.48 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| 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 | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |