Fairfield, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.7 °C (low) to 12.9 °C (high). Annual precipitation averages 1093.5 Millimeters. Fairfield 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 | -12.7 °C | -1.8 °C | 76.96 mm |
| February | -11.9 °C | -0.1 °C | 65.53 mm |
| March | -6.2 °C | 4.7 °C | 78.74 mm |
| April | 0.2 °C | 11.9 °C | 93.98 mm |
| May | 6.3 °C | 18.7 °C | 86.61 mm |
| June | 11.7 °C | 23.5 °C | 102.11 mm |
| July | 14.9 °C | 26.5 °C | 86.61 mm |
| August | 14.1 °C | 26.1 °C | 89.66 mm |
| September | 9.8 °C | 21.8 °C | 94.23 mm |
| October | 3.7 °C | 14.7 °C | 125.48 mm |
| November | -1.8 °C | 7.7 °C | 96.52 mm |
| December | -8 °C | 1.5 °C | 97.03 mm |
| Annual | 1.7 °C | 12.9 °C | 1093.46 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 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |