South Windham, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 36 °F (low) to 56.5 °F (high). Annual precipitation averages 49.8 Inches. South Windham 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. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 11.6 °F | 31.0 °F | 3.49 in. |
| February | 12.3 °F | 34.1 °F | 3.56 in. |
| March | 22.1 °F | 42.2 °F | 4.11 in. |
| April | 33.1 °F | 54.2 °F | 4.5 in. |
| May | 43.6 °F | 65.7 °F | 3.69 in. |
| June | 53.8 °F | 74.6 °F | 4.53 in. |
| July | 59.8 °F | 80.5 °F | 3.83 in. |
| August | 57.8 °F | 79.5 °F | 3.56 in. |
| September | 50.0 °F | 72.0 °F | 3.92 in. |
| October | 39.1 °F | 59.5 °F | 5.6 in. |
| November | 29.4 °F | 47.3 °F | 4.34 in. |
| December | 19.1 °F | 36.8 °F | 4.69 in. |
| Annual | 36 °F | 56.5 °F | 49.82 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |