South Lancaster, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 38.6 °F (low) to 59.7 °F (high). Annual precipitation averages 49.7 Inches. South Lancaster is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 15.7 °F | 34.8 °F | 3.8 in. |
| February | 17.3 °F | 37.3 °F | 3.37 in. |
| March | 25.3 °F | 45.1 °F | 4.48 in. |
| April | 35.8 °F | 58.1 °F | 4.25 in. |
| May | 46.5 °F | 69.0 °F | 3.69 in. |
| June | 56.1 °F | 77.6 °F | 4.36 in. |
| July | 61.8 °F | 83.4 °F | 3.86 in. |
| August | 60.2 °F | 81.9 °F | 4.34 in. |
| September | 51.8 °F | 75.0 °F | 4.12 in. |
| October | 40.3 °F | 62.7 °F | 4.96 in. |
| November | 30.7 °F | 51.2 °F | 3.9 in. |
| December | 22.2 °F | 40.6 °F | 4.6 in. |
| Annual | 38.6 °F | 59.7 °F | 49.73 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |