Boscawen, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.7 °C (low) to 13.8 °C (high). Annual precipitation averages 1225.8 Millimeters. Boscawen is located in USDA Plant Hardiness Zone 5b. 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 | -11.4 °C | -0.8 °C | 83.31 mm |
| February | -10.6 °C | 1.1 °C | 82.55 mm |
| March | -6.2 °C | 5.6 °C | 95.25 mm |
| April | 0.1 °C | 13.1 °C | 99.82 mm |
| May | 6.3 °C | 19.8 °C | 93.73 mm |
| June | 11.6 °C | 24.6 °C | 111.51 mm |
| July | 14.6 °C | 27.5 °C | 115.32 mm |
| August | 13.4 °C | 26.6 °C | 97.79 mm |
| September | 9.2 °C | 22.4 °C | 96.01 mm |
| October | 2.8 °C | 15 °C | 129.79 mm |
| November | -2.2 °C | 8.3 °C | 102.62 mm |
| December | -7.4 °C | 2.2 °C | 118.11 mm |
| Annual | 1.7 °C | 13.8 °C | 1225.81 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 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |