South Thomaston, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 38.1 °F (low) to 53.7 °F (high). Annual precipitation averages 51.2 Inches. South Thomaston is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 16.8 °F | 31.8 °F | 4.48 in. |
| February | 17.7 °F | 33.4 °F | 3.76 in. |
| March | 24.7 °F | 39.8 °F | 4.76 in. |
| April | 34.7 °F | 50.3 °F | 4.68 in. |
| May | 43.7 °F | 60.0 °F | 3.76 in. |
| June | 52.2 °F | 68.7 °F | 4.01 in. |
| July | 58.2 °F | 74.8 °F | 3.25 in. |
| August | 57.7 °F | 74.6 °F | 2.99 in. |
| September | 51.6 °F | 68.2 °F | 4.42 in. |
| October | 42.2 °F | 57.1 °F | 5.24 in. |
| November | 33.6 °F | 47.4 °F | 4.86 in. |
| December | 23.8 °F | 37.7 °F | 4.96 in. |
| Annual | 38.1 °F | 53.7 °F | 51.17 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |