Wilmington, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 4.4 °C (low) to 15.5 °C (high). Annual precipitation averages 1253 Millimeters. Wilmington 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 | -7.9 °C | 2.1 °C | 97.03 mm |
| February | -6.9 °C | 3.6 °C | 89.92 mm |
| March | -2.9 °C | 7.6 °C | 119.63 mm |
| April | 2.8 °C | 14.4 °C | 107.95 mm |
| May | 8.3 °C | 20.1 °C | 95 mm |
| June | 13.6 °C | 25.1 °C | 108.46 mm |
| July | 16.8 °C | 28.4 °C | 97.28 mm |
| August | 16 °C | 27.6 °C | 95.25 mm |
| September | 11.8 °C | 23.6 °C | 97.54 mm |
| October | 5.4 °C | 16.8 °C | 122.68 mm |
| November | 0.3 °C | 10.9 °C | 100.58 mm |
| December | -4.3 °C | 5.2 °C | 121.67 mm |
| Annual | 4.4 °C | 15.5 °C | 1252.99 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 |