Sudbury, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.9 °C (low) to 15.7 °C (high). Annual precipitation averages 1227.8 Millimeters. Sudbury 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 | -8.4 °C | 2.1 °C | 93.98 mm |
| February | -7.6 °C | 3.6 °C | 83.82 mm |
| March | -3.3 °C | 7.8 °C | 112.52 mm |
| April | 2.3 °C | 14.8 °C | 106.93 mm |
| May | 8 °C | 20.5 °C | 93.73 mm |
| June | 13.2 °C | 25.2 °C | 109.22 mm |
| July | 16.5 °C | 28.6 °C | 93.47 mm |
| August | 15.7 °C | 27.8 °C | 98.81 mm |
| September | 11.2 °C | 24.1 °C | 96.27 mm |
| October | 4.9 °C | 17.2 °C | 122.94 mm |
| November | -0.3 °C | 11.1 °C | 97.79 mm |
| December | -4.9 °C | 5.3 °C | 118.36 mm |
| Annual | 3.9 °C | 15.7 °C | 1227.84 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 |