Lancaster, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -0.9 °C (low) to 12.1 °C (high). Annual precipitation averages 1017.5 Millimeters. Lancaster is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -15.9 °C | -3.6 °C | 61.72 mm |
| February | -15.4 °C | -1.5 °C | 51.31 mm |
| March | -9.4 °C | 3.6 °C | 54.86 mm |
| April | -1.8 °C | 11.3 °C | 80.26 mm |
| May | 4.4 °C | 19.1 °C | 99.82 mm |
| June | 9.7 °C | 23.7 °C | 114.3 mm |
| July | 12.4 °C | 26.3 °C | 109.47 mm |
| August | 11.4 °C | 25.5 °C | 105.41 mm |
| September | 7.2 °C | 21.3 °C | 91.44 mm |
| October | 1.2 °C | 13.6 °C | 103.12 mm |
| November | -4.1 °C | 6.2 °C | 71.37 mm |
| December | -10.7 °C | -0.4 °C | 74.42 mm |
| Annual | -0.9 °C | 12.1 °C | 1017.5 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 4b : -31.7°C to -28.9°C |
| Plant Hardiness Zone - 2012 | Zone 4a : -34.4°C to -31.7°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |