Somersworth, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 37.3 °F (low) to 57.4 °F (high). Annual precipitation averages 46.3 Inches. Somersworth 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. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 14.4 °F | 32.5 °F | 3.29 in. |
| February | 15.9 °F | 35.2 °F | 3.25 in. |
| March | 24.3 °F | 42.8 °F | 4.12 in. |
| April | 34.5 °F | 55.6 °F | 4.26 in. |
| May | 44.7 °F | 66.3 °F | 3.6 in. |
| June | 54.2 °F | 75.7 °F | 4.07 in. |
| July | 59.8 °F | 81.3 °F | 3.67 in. |
| August | 58.3 °F | 80.2 °F | 3.45 in. |
| September | 50.6 °F | 72.9 °F | 3.57 in. |
| October | 39.5 °F | 60.3 °F | 4.76 in. |
| November | 30.3 °F | 48.7 °F | 3.85 in. |
| December | 21.2 °F | 37.8 °F | 4.36 in. |
| Annual | 37.3 °F | 57.4 °F | 46.25 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |