East Merrimack, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.8 °C (low) to 15.2 °C (high). Annual precipitation averages 1160.8 Millimeters. 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 | -10.3 °C | 1.1 °C | 82.8 mm |
| February | -9.4 °C | 2.8 °C | 80.26 mm |
| March | -4.7 °C | 7.2 °C | 100.08 mm |
| April | 1.3 °C | 14.5 °C | 99.82 mm |
| May | 7.5 °C | 20.7 °C | 92.46 mm |
| June | 12.7 °C | 25.7 °C | 104.65 mm |
| July | 15.9 °C | 28.7 °C | 90.68 mm |
| August | 14.9 °C | 27.8 °C | 92.71 mm |
| September | 10.4 °C | 23.7 °C | 95.5 mm |
| October | 3.6 °C | 16.6 °C | 119.38 mm |
| November | -1.7 °C | 9.9 °C | 95 mm |
| December | -6.5 °C | 4.2 °C | 107.44 mm |
| Annual | 2.8 °C | 15.2 °C | 1160.78 mm |
| 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 : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |