Plymouth, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 5.9 °C (low) to 15.6 °C (high). Annual precipitation averages 1322.8 Millimeters. Plymouth 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 | -5.3 °C | 3.8 °C | 113.28 mm |
| February | -4.9 °C | 4.6 °C | 102.36 mm |
| March | -1.6 °C | 7.9 °C | 144.02 mm |
| April | 3.4 °C | 13.8 °C | 115.82 mm |
| May | 8.8 °C | 19.2 °C | 94.49 mm |
| June | 14 °C | 24.3 °C | 98.3 mm |
| July | 17.7 °C | 27.6 °C | 88.65 mm |
| August | 17 °C | 26.7 °C | 93.73 mm |
| September | 13.3 °C | 23.2 °C | 105.16 mm |
| October | 7.6 °C | 17.3 °C | 122.17 mm |
| November | 2.4 °C | 11.8 °C | 116.59 mm |
| December | -2.1 °C | 6.8 °C | 128.27 mm |
| Annual | 5.9 °C | 15.6 °C | 1322.84 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 | Dfb - Humid Continental Mild Summer, Wet All Year |