Dexter, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 32.4 °F (low) to 53.3 °F (high). Annual precipitation averages 45.1 Inches. 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 | 5.8 °F | 25.7 °F | 3.36 in. |
| February | 7.3 °F | 29.4 °F | 2.78 in. |
| March | 17.7 °F | 38.4 °F | 3.4 in. |
| April | 29.9 °F | 51.4 °F | 3.74 in. |
| May | 41.2 °F | 64.5 °F | 3.73 in. |
| June | 50.8 °F | 72.9 °F | 4.49 in. |
| July | 56.5 °F | 78.5 °F | 3.63 in. |
| August | 54.8 °F | 77.3 °F | 3.53 in. |
| September | 46.8 °F | 69.8 °F | 3.73 in. |
| October | 36.2 °F | 56.4 °F | 4.83 in. |
| November | 26.7 °F | 43.6 °F | 3.97 in. |
| December | 15.0 °F | 32.1 °F | 3.9 in. |
| Annual | 32.4 °F | 53.3 °F | 45.09 in. |
| 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 : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |