South Duxbury, Massachusetts has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6 °C (low) to 15.5 °C (high). Annual precipitation averages 1331.2 Millimeters. South Duxbury is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -5.1 °C | 3.7 °C | 113.28 mm |
| February | -4.6 °C | 4.6 °C | 102.87 mm |
| March | -1.4 °C | 7.8 °C | 143.76 mm |
| April | 3.5 °C | 13.6 °C | 116.84 mm |
| May | 9 °C | 19.2 °C | 95 mm |
| June | 14.1 °C | 24.3 °C | 99.06 mm |
| July | 17.7 °C | 27.6 °C | 88.9 mm |
| August | 17.1 °C | 26.6 °C | 93.73 mm |
| September | 13.4 °C | 23.1 °C | 107.19 mm |
| October | 7.8 °C | 17.2 °C | 124.21 mm |
| November | 2.6 °C | 11.7 °C | 117.86 mm |
| December | -1.7 °C | 6.8 °C | 128.52 mm |
| Annual | 6 °C | 15.5 °C | 1331.22 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |