Dalton, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 29.6 °F (low) to 52.1 °F (high). Annual precipitation averages 43.7 Inches. 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 | 5.2 °F | 25.6 °F | 2.79 in. |
| February | 5.9 °F | 28.5 °F | 2.39 in. |
| March | 14.8 °F | 37.4 °F | 2.45 in. |
| April | 27.4 °F | 50.3 °F | 3.56 in. |
| May | 38.3 °F | 63.8 °F | 3.93 in. |
| June | 47.5 °F | 72.0 °F | 4.52 in. |
| July | 52.3 °F | 76.4 °F | 4.61 in. |
| August | 50.4 °F | 74.9 °F | 4.26 in. |
| September | 43.4 °F | 67.9 °F | 3.61 in. |
| October | 33.8 °F | 54.5 °F | 4.6 in. |
| November | 23.8 °F | 42.3 °F | 3.25 in. |
| December | 12.9 °F | 31.3 °F | 3.71 in. |
| Annual | 29.6 °F | 52.1 °F | 43.68 in. |
| 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 : -25°F to -20°F |
| Plant Hardiness Zone - 2012 | Zone 4a : -30°F to -25°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |