Webster, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.5 °C (low) to 15.3 °C (high). Annual precipitation averages 1268.5 Millimeters. Webster 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 | -8.6 °C | 2.1 °C | 97.79 mm |
| February | -8 °C | 3.4 °C | 83.31 mm |
| March | -3.8 °C | 7.7 °C | 113.54 mm |
| April | 1.8 °C | 14.6 °C | 113.03 mm |
| May | 7.6 °C | 20.6 °C | 90.68 mm |
| June | 12.7 °C | 25 °C | 110.24 mm |
| July | 16.1 °C | 27.9 °C | 100.33 mm |
| August | 14.9 °C | 27 °C | 109.47 mm |
| September | 10.9 °C | 23.2 °C | 108.2 mm |
| October | 4.7 °C | 16.6 °C | 126.49 mm |
| November | -0.6 °C | 10.6 °C | 98.55 mm |
| December | -5.2 °C | 4.9 °C | 116.84 mm |
| Annual | 3.5 °C | 15.3 °C | 1268.47 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 |