Fort Fairfield, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -0.9 °C (low) to 10.4 °C (high). Annual precipitation averages 1094.5 Millimeters. Fort Fairfield is located in USDA Plant Hardiness Zone 4a. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -17.1 °C | -5.9 °C | 88.9 mm |
| February | -16.6 °C | -4.3 °C | 65.79 mm |
| March | -9.9 °C | 1.2 °C | 73.91 mm |
| April | -1.9 °C | 8.9 °C | 84.07 mm |
| May | 4.6 °C | 17.4 °C | 91.19 mm |
| June | 9.8 °C | 22.5 °C | 104.65 mm |
| July | 13.3 °C | 25.2 °C | 111.25 mm |
| August | 12.1 °C | 24.6 °C | 98.04 mm |
| September | 8 °C | 20.1 °C | 92.2 mm |
| October | 1.9 °C | 12.2 °C | 101.09 mm |
| November | -3.7 °C | 4.5 °C | 86.87 mm |
| December | -11 °C | -2 °C | 96.52 mm |
| Annual | -0.9 °C | 10.4 °C | 1094.48 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 4a : -34.4°C to -31.7°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 |