East Merrimack, 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 59.4 °F (high). Annual precipitation averages 45.7 Inches. East Merrimack is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 13.4 °F | 33.9 °F | 3.26 in. |
| February | 15.1 °F | 37.1 °F | 3.16 in. |
| March | 23.6 °F | 44.9 °F | 3.94 in. |
| April | 34.3 °F | 58.1 °F | 3.93 in. |
| May | 45.5 °F | 69.2 °F | 3.64 in. |
| June | 54.9 °F | 78.3 °F | 4.12 in. |
| July | 60.6 °F | 83.6 °F | 3.57 in. |
| August | 58.9 °F | 82.0 °F | 3.65 in. |
| September | 50.8 °F | 74.6 °F | 3.76 in. |
| October | 38.5 °F | 61.9 °F | 4.7 in. |
| November | 29.0 °F | 49.9 °F | 3.74 in. |
| December | 20.3 °F | 39.5 °F | 4.23 in. |
| Annual | 37.1 °F | 59.4 °F | 45.7 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| 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 | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |