Sterling, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.3 °C (low) to 14.2 °C (high). Annual precipitation averages 1310.4 Millimeters. Sterling is located in USDA Plant Hardiness Zone 6a. 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 | -9.6 °C | 0.4 °C | 101.85 mm |
| February | -8.8 °C | 1.9 °C | 91.19 mm |
| March | -4.4 °C | 6.2 °C | 118.36 mm |
| April | 1.6 °C | 13.4 °C | 111 mm |
| May | 7.7 °C | 19.6 °C | 99.06 mm |
| June | 12.8 °C | 24.3 °C | 112.52 mm |
| July | 16 °C | 27.3 °C | 99.06 mm |
| August | 15.1 °C | 26.4 °C | 106.43 mm |
| September | 10.8 °C | 22.6 °C | 111.51 mm |
| October | 4.4 °C | 15.7 °C | 133.6 mm |
| November | -0.8 °C | 9.4 °C | 105.16 mm |
| December | -5.8 °C | 3.6 °C | 120.65 mm |
| Annual | 3.3 °C | 14.2 °C | 1310.39 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 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |