Salem, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.6 °C (low) to 15.3 °C (high). Annual precipitation averages 1203 Millimeters. Salem 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 | -9.1 °C | 1.5 °C | 85.85 mm |
| February | -8.1 °C | 3.1 °C | 83.82 mm |
| March | -3.8 °C | 7.3 °C | 109.47 mm |
| April | 1.9 °C | 14.4 °C | 101.6 mm |
| May | 7.8 °C | 20.3 °C | 97.54 mm |
| June | 13.1 °C | 25.3 °C | 108.46 mm |
| July | 16.3 °C | 28.5 °C | 93.22 mm |
| August | 15.3 °C | 27.7 °C | 93.22 mm |
| September | 11 °C | 23.6 °C | 98.81 mm |
| October | 4.4 °C | 16.7 °C | 122.43 mm |
| November | -0.7 °C | 10.3 °C | 97.03 mm |
| December | -5.5 °C | 4.6 °C | 111.51 mm |
| Annual | 3.6 °C | 15.3 °C | 1202.96 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 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |