Dalton, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -1.3 °C (low) to 11.2 °C (high). Annual precipitation averages 1109.5 Millimeters. Dalton is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -14.9 °C | -3.6 °C | 70.87 mm |
| February | -14.5 °C | -1.9 °C | 60.71 mm |
| March | -9.6 °C | 3 °C | 62.23 mm |
| April | -2.6 °C | 10.2 °C | 90.42 mm |
| May | 3.5 °C | 17.7 °C | 99.82 mm |
| June | 8.6 °C | 22.2 °C | 114.81 mm |
| July | 11.3 °C | 24.7 °C | 117.09 mm |
| August | 10.2 °C | 23.8 °C | 108.2 mm |
| September | 6.3 °C | 19.9 °C | 91.69 mm |
| October | 1 °C | 12.5 °C | 116.84 mm |
| November | -4.6 °C | 5.7 °C | 82.55 mm |
| December | -10.6 °C | -0.4 °C | 94.23 mm |
| Annual | -1.3 °C | 11.2 °C | 1109.46 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 4b : -31.7°C to -28.9°C |
| Plant Hardiness Zone - 2012 | Zone 4a : -34.4°C to -31.7°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |