Dexter, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.2 °C (low) to 11.9 °C (high). Annual precipitation averages 1145.3 Millimeters. Dexter is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -14.6 °C | -3.5 °C | 85.34 mm |
| February | -13.7 °C | -1.4 °C | 70.61 mm |
| March | -7.9 °C | 3.6 °C | 86.36 mm |
| April | -1.2 °C | 10.8 °C | 95 mm |
| May | 5.1 °C | 18.1 °C | 94.74 mm |
| June | 10.4 °C | 22.7 °C | 114.05 mm |
| July | 13.6 °C | 25.8 °C | 92.2 mm |
| August | 12.7 °C | 25.2 °C | 89.66 mm |
| September | 8.2 °C | 21 °C | 94.74 mm |
| October | 2.3 °C | 13.6 °C | 122.68 mm |
| November | -2.9 °C | 6.4 °C | 100.84 mm |
| December | -9.4 °C | 0.1 °C | 99.06 mm |
| Annual | 0.2 °C | 11.9 °C | 1145.28 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| 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 |