Lyme, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.7 °C (low) to 11.2 °C (high). Annual precipitation averages 1126.7 Millimeters. Lyme is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -13.4 °C | -3.5 °C | 73.66 mm |
| February | -12.7 °C | -1.9 °C | 62.48 mm |
| March | -7.6 °C | 2.9 °C | 77.47 mm |
| April | -0.4 °C | 10.6 °C | 89.15 mm |
| May | 5.7 °C | 17.8 °C | 95.25 mm |
| June | 11.1 °C | 22.1 °C | 105.92 mm |
| July | 13.7 °C | 24.8 °C | 115.32 mm |
| August | 12.8 °C | 24 °C | 103.89 mm |
| September | 8.7 °C | 20 °C | 100.58 mm |
| October | 2.6 °C | 12.7 °C | 122.17 mm |
| November | -2.8 °C | 5.7 °C | 85.6 mm |
| December | -9 °C | -0.4 °C | 95.25 mm |
| Annual | 0.7 °C | 11.2 °C | 1126.74 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| 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 |