Windsor, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2 °C (low) to 12.7 °C (high). Annual precipitation averages 1201.7 Millimeters. Windsor is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -12.1 °C | -1.7 °C | 88.9 mm |
| February | -11 °C | 0.1 °C | 78.23 mm |
| March | -5.7 °C | 4.6 °C | 97.28 mm |
| April | 0.6 °C | 11.6 °C | 106.43 mm |
| May | 6.5 °C | 18.1 °C | 90.68 mm |
| June | 11.8 °C | 22.9 °C | 108.97 mm |
| July | 15.1 °C | 26.1 °C | 85.6 mm |
| August | 14.2 °C | 25.6 °C | 89.41 mm |
| September | 10 °C | 21.5 °C | 98.55 mm |
| October | 3.9 °C | 14.4 °C | 135.38 mm |
| November | -1.6 °C | 7.7 °C | 111.76 mm |
| December | -7.4 °C | 1.7 °C | 110.49 mm |
| Annual | 2 °C | 12.7 °C | 1201.68 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |