Wiscasset, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.4 °C (low) to 12.9 °C (high). Annual precipitation averages 1271 Millimeters. Wiscasset is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -11.2 °C | -0.7 °C | 98.81 mm |
| February | -9.9 °C | 0.9 °C | 91.19 mm |
| March | -4.8 °C | 5.1 °C | 111 mm |
| April | 0.7 °C | 11.4 °C | 113.54 mm |
| May | 6.4 °C | 17.6 °C | 93.73 mm |
| June | 11.5 °C | 22.4 °C | 114.3 mm |
| July | 14.9 °C | 25.7 °C | 89.15 mm |
| August | 14.2 °C | 25.3 °C | 80.52 mm |
| September | 10.3 °C | 21.3 °C | 100.84 mm |
| October | 4.4 °C | 14.6 °C | 138.68 mm |
| November | -1 °C | 8.4 °C | 116.59 mm |
| December | -6.8 °C | 2.6 °C | 122.68 mm |
| Annual | 2.4 °C | 12.9 °C | 1271.03 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |