South Yarmouth, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 6.8 °C (low) to 14.2 °C (high). Annual precipitation averages 1237.2 Millimeters. South Yarmouth is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -3.9 °C | 3.4 °C | 113.54 mm |
| February | -3.6 °C | 3.9 °C | 93.98 mm |
| March | -0.7 °C | 6.6 °C | 118.11 mm |
| April | 4 °C | 11.4 °C | 113.79 mm |
| May | 9.1 °C | 16.7 °C | 87.12 mm |
| June | 14.2 °C | 21.7 °C | 87.12 mm |
| July | 18.2 °C | 25.6 °C | 72.14 mm |
| August | 17.8 °C | 25.2 °C | 83.57 mm |
| September | 14.6 °C | 21.9 °C | 110.74 mm |
| October | 9 °C | 16.3 °C | 118.36 mm |
| November | 3.9 °C | 11.2 °C | 102.11 mm |
| December | -0.6 °C | 6.7 °C | 136.65 mm |
| Annual | 6.8 °C | 14.2 °C | 1237.23 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7b : -15°C to -12.2°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |