Mason, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.7 °C (low) to 14.1 °C (high). Annual precipitation averages 1266.2 Millimeters. Mason is located in USDA Plant Hardiness Zone 6a. 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 | -10 °C | 0.1 °C | 91.69 mm |
| February | -9.2 °C | 1.8 °C | 85.09 mm |
| March | -4.9 °C | 6.1 °C | 109.22 mm |
| April | 1.1 °C | 13.3 °C | 106.43 mm |
| May | 7.2 °C | 19.6 °C | 100.33 mm |
| June | 12.3 °C | 24.5 °C | 112.01 mm |
| July | 15.4 °C | 27.4 °C | 104.65 mm |
| August | 14.3 °C | 26.4 °C | 100.84 mm |
| September | 10.2 °C | 22.5 °C | 105.92 mm |
| October | 3.8 °C | 15.3 °C | 131.83 mm |
| November | -1.4 °C | 9.1 °C | 102.62 mm |
| December | -6.4 °C | 3.1 °C | 115.57 mm |
| Annual | 2.7 °C | 14.1 °C | 1266.2 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°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 |