Hartland, Vermont has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.1 °C (low) to 13.3 °C (high). Annual precipitation averages 1043.9 Millimeters. Hartland is located in USDA Plant Hardiness Zone 5a. 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 | -12.9 °C | -1.8 °C | 70.36 mm |
| February | -12.2 °C | 0.2 °C | 62.23 mm |
| March | -7.1 °C | 5 °C | 74.42 mm |
| April | -0.4 °C | 12.7 °C | 86.11 mm |
| May | 6.2 °C | 19.7 °C | 86.87 mm |
| June | 11.2 °C | 24.3 °C | 103.12 mm |
| July | 14.2 °C | 27.1 °C | 106.68 mm |
| August | 13.1 °C | 26.2 °C | 87.12 mm |
| September | 9 °C | 22.3 °C | 85.85 mm |
| October | 2.6 °C | 14.5 °C | 111.76 mm |
| November | -2.7 °C | 7.7 °C | 77.72 mm |
| December | -8.2 °C | 1.3 °C | 91.69 mm |
| Annual | 1.1 °C | 13.3 °C | 1043.93 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 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |