Swanville, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.7 °C (low) to 12.3 °C (high). Annual precipitation averages 1234.4 Millimeters. Swanville 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 | -12.9 °C | -2.3 °C | 98.04 mm |
| February | -12.1 °C | -0.6 °C | 83.31 mm |
| March | -6.4 °C | 4 °C | 100.58 mm |
| April | 0.4 °C | 11.1 °C | 111.51 mm |
| May | 6.4 °C | 17.8 °C | 95.5 mm |
| June | 11.6 °C | 22.7 °C | 107.7 mm |
| July | 14.9 °C | 25.9 °C | 81.79 mm |
| August | 14.1 °C | 25.4 °C | 85.09 mm |
| September | 9.7 °C | 21.1 °C | 99.57 mm |
| October | 3.7 °C | 14 °C | 137.92 mm |
| November | -1.7 °C | 7.2 °C | 115.82 mm |
| December | -7.9 °C | 1.1 °C | 117.6 mm |
| Annual | 1.7 °C | 12.3 °C | 1234.43 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 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |