Deerfield, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.7 °C (low) to 15.1 °C (high). Annual precipitation averages 1265.7 Millimeters. Deerfield is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -10.2 °C | 0.7 °C | 90.17 mm |
| February | -9.5 °C | 2.6 °C | 80.77 mm |
| March | -4.7 °C | 7.2 °C | 95.5 mm |
| April | 1.2 °C | 14.5 °C | 98.3 mm |
| May | 7.3 °C | 20.9 °C | 101.09 mm |
| June | 12.7 °C | 25.8 °C | 123.44 mm |
| July | 15.5 °C | 28.7 °C | 107.19 mm |
| August | 14.5 °C | 27.7 °C | 115.06 mm |
| September | 10.1 °C | 23.6 °C | 121.41 mm |
| October | 3.7 °C | 16.3 °C | 124.97 mm |
| November | -1.6 °C | 9.6 °C | 93.98 mm |
| December | -6.3 °C | 3.7 °C | 113.79 mm |
| Annual | 2.7 °C | 15.1 °C | 1265.67 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |