Palmyra, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.6 °C (low) to 12.6 °C (high). Annual precipitation averages 1153.7 Millimeters. Palmyra 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 Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -14.3 °C | -2.8 °C | 88.65 mm |
| February | -13.6 °C | -0.8 °C | 72.9 mm |
| March | -7.4 °C | 4.2 °C | 91.95 mm |
| April | -0.7 °C | 11.6 °C | 99.31 mm |
| May | 5.6 °C | 18.8 °C | 88.14 mm |
| June | 10.9 °C | 23.5 °C | 106.68 mm |
| July | 14.1 °C | 26.5 °C | 85.6 mm |
| August | 13.1 °C | 25.9 °C | 89.15 mm |
| September | 8.7 °C | 21.7 °C | 95.5 mm |
| October | 2.6 °C | 14.3 °C | 120.65 mm |
| November | -2.7 °C | 7.1 °C | 107.44 mm |
| December | -9.2 °C | 0.7 °C | 107.7 mm |
| Annual | 0.6 °C | 12.6 °C | 1153.67 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| 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 | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |