Alexandria, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.4 °C (low) to 11 °C (high). Annual precipitation averages 1461.8 Millimeters. Alexandria is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -13.7 °C | -4.2 °C | 91.69 mm |
| February | -12.8 °C | -2.2 °C | 85.09 mm |
| March | -8.1 °C | 2.8 °C | 111.76 mm |
| April | -1 °C | 10.3 °C | 117.6 mm |
| May | 5.5 °C | 17.6 °C | 126.49 mm |
| June | 10.6 °C | 22.2 °C | 147.83 mm |
| July | 13.1 °C | 24.8 °C | 125.22 mm |
| August | 12.6 °C | 23.9 °C | 113.79 mm |
| September | 8.6 °C | 19.8 °C | 115.82 mm |
| October | 2.4 °C | 12.6 °C | 164.34 mm |
| November | -3.3 °C | 5 °C | 123.95 mm |
| December | -9.4 °C | -1.1 °C | 138.18 mm |
| Annual | 0.4 °C | 11 °C | 1461.76 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°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 |