Winchester, Massachusetts has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5 °C (low) to 15.5 °C (high). Annual precipitation averages 1285.2 Millimeters. Winchester 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. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -7.3 °C | 2.4 °C | 102.87 mm |
| February | -6.4 °C | 3.9 °C | 94.23 mm |
| March | -2.3 °C | 7.7 °C | 124.46 mm |
| April | 3.3 °C | 14.3 °C | 111 mm |
| May | 8.9 °C | 20 °C | 94.74 mm |
| June | 14.2 °C | 25.1 °C | 108.71 mm |
| July | 17.4 °C | 28.3 °C | 98.04 mm |
| August | 16.7 °C | 27.4 °C | 96.27 mm |
| September | 12.5 °C | 23.5 °C | 99.82 mm |
| October | 6.2 °C | 17 °C | 125.22 mm |
| November | 0.9 °C | 11.2 °C | 104.9 mm |
| December | -3.7 °C | 5.5 °C | 124.97 mm |
| Annual | 5 °C | 15.5 °C | 1285.23 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |