Lebanon, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.3 °C (low) to 13.5 °C (high). Annual precipitation averages 1055.4 Millimeters. Lebanon is located in USDA Plant Hardiness Zone 5a. 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 | -12.8 °C | -1.7 °C | 70.36 mm |
| February | -12.1 °C | 0.3 °C | 61.72 mm |
| March | -6.8 °C | 5.1 °C | 80.26 mm |
| April | -0.1 °C | 13 °C | 82.8 mm |
| May | 6.3 °C | 20.1 °C | 87.38 mm |
| June | 11.4 °C | 24.6 °C | 105.92 mm |
| July | 14.3 °C | 27.4 °C | 108.97 mm |
| August | 13.3 °C | 26.5 °C | 91.44 mm |
| September | 9.2 °C | 22.6 °C | 88.39 mm |
| October | 2.8 °C | 14.8 °C | 110.74 mm |
| November | -2.4 °C | 7.8 °C | 79.76 mm |
| December | -8.1 °C | 1.3 °C | 87.63 mm |
| Annual | 1.3 °C | 13.5 °C | 1055.37 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |