Medfield, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 4.4 °C (low) to 15.8 °C (high). Annual precipitation averages 1256.8 Millimeters. Medfield is located in USDA Plant Hardiness Zone 6b. 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 | -7.7 °C | 2.6 °C | 100.84 mm |
| February | -6.9 °C | 4 °C | 86.36 mm |
| March | -2.8 °C | 8 °C | 120.4 mm |
| April | 2.7 °C | 14.7 °C | 112.78 mm |
| May | 8.3 °C | 20.5 °C | 90.93 mm |
| June | 13.4 °C | 25.3 °C | 106.43 mm |
| July | 16.8 °C | 28.4 °C | 90.68 mm |
| August | 15.9 °C | 27.7 °C | 99.57 mm |
| September | 11.8 °C | 23.8 °C | 97.54 mm |
| October | 5.3 °C | 17.2 °C | 124.97 mm |
| November | 0.3 °C | 11.2 °C | 104.39 mm |
| December | -4.3 °C | 5.6 °C | 121.92 mm |
| Annual | 4.4 °C | 15.8 °C | 1256.81 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |