New London, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 36 °F (low) to 54.8 °F (high). Annual precipitation averages 49 Inches. New London is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 12.5 °F | 28.8 °F | 3.34 in. |
| February | 14.1 °F | 31.8 °F | 3.06 in. |
| March | 21.8 °F | 40.1 °F | 3.64 in. |
| April | 32.6 °F | 53.4 °F | 3.93 in. |
| May | 44.0 °F | 66.1 °F | 3.96 in. |
| June | 53.6 °F | 74.3 °F | 4.62 in. |
| July | 58.7 °F | 78.8 °F | 4.57 in. |
| August | 57.4 °F | 77.5 °F | 4.14 in. |
| September | 50.0 °F | 70.3 °F | 3.98 in. |
| October | 38.7 °F | 56.8 °F | 5.34 in. |
| November | 29.5 °F | 45.6 °F | 4.0 in. |
| December | 19.3 °F | 34.0 °F | 4.38 in. |
| Annual | 36 °F | 54.8 °F | 48.96 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |