Seabrook, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.9 °C (low) to 14.6 °C (high). Annual precipitation averages 1268.2 Millimeters. Seabrook is located in USDA Plant Hardiness Zone 6b. 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 | -8.4 °C | 1.4 °C | 95.76 mm |
| February | -7.7 °C | 2.8 °C | 92.46 mm |
| March | -3.4 °C | 6.7 °C | 118.87 mm |
| April | 1.9 °C | 13.4 °C | 111 mm |
| May | 7.6 °C | 18.9 °C | 105.41 mm |
| June | 13.1 °C | 24.3 °C | 113.28 mm |
| July | 16.4 °C | 27.7 °C | 90.42 mm |
| August | 15.6 °C | 27 °C | 90.17 mm |
| September | 11.5 °C | 22.9 °C | 101.09 mm |
| October | 5.2 °C | 16.1 °C | 127.25 mm |
| November | -0.1 °C | 10 °C | 101.09 mm |
| December | -4.8 °C | 4.3 °C | 121.41 mm |
| Annual | 3.9 °C | 14.6 °C | 1268.21 mm |
| 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 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |