Milton, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 37.1 °F (low) to 56.8 °F (high). Annual precipitation averages 49 Inches. Milton is located in USDA Plant Hardiness Zone 5b. 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 | 13.9 °F | 31.0 °F | 3.49 in. |
| February | 14.7 °F | 33.9 °F | 3.4 in. |
| March | 23.1 °F | 41.7 °F | 4.24 in. |
| April | 33.8 °F | 55.4 °F | 4.25 in. |
| May | 44.8 °F | 66.9 °F | 3.77 in. |
| June | 54.4 °F | 76.0 °F | 4.41 in. |
| July | 59.9 °F | 81.5 °F | 4.08 in. |
| August | 58.5 °F | 79.9 °F | 3.84 in. |
| September | 50.9 °F | 72.1 °F | 3.86 in. |
| October | 40.1 °F | 59.1 °F | 4.99 in. |
| November | 30.1 °F | 47.2 °F | 4.16 in. |
| December | 20.8 °F | 36.5 °F | 4.53 in. |
| Annual | 37.1 °F | 56.8 °F | 49.02 in. |
| 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 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |