Northborough, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.7 °C (low) to 15.3 °C (high). Annual precipitation averages 1245.6 Millimeters. Northborough is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9 °C | 1.6 °C | 95.76 mm |
| February | -8.2 °C | 3.1 °C | 84.07 mm |
| March | -3.7 °C | 7.3 °C | 113.54 mm |
| April | 2.1 °C | 14.4 °C | 108.2 mm |
| May | 8.1 °C | 20.4 °C | 90.68 mm |
| June | 13.3 °C | 25.1 °C | 107.44 mm |
| July | 16.4 °C | 28.3 °C | 98.04 mm |
| August | 15.6 °C | 27.4 °C | 107.7 mm |
| September | 10.9 °C | 23.7 °C | 101.09 mm |
| October | 4.6 °C | 16.9 °C | 124.46 mm |
| November | -0.7 °C | 10.7 °C | 97.79 mm |
| December | -5.3 °C | 4.8 °C | 116.84 mm |
| Annual | 3.7 °C | 15.3 °C | 1245.61 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| 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 | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |