Wilton, Connecticut has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.4 °C (low) to 16 °C (high). Annual precipitation averages 1286.8 Millimeters. Wilton is located in USDA Plant Hardiness Zone 7a. 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 | -6.7 °C | 2.7 °C | 100.33 mm |
| February | -5.8 °C | 4.2 °C | 77.47 mm |
| March | -1.8 °C | 8.4 °C | 107.44 mm |
| April | 3.9 °C | 15.6 °C | 103.38 mm |
| May | 9.3 °C | 21.3 °C | 98.04 mm |
| June | 14.6 °C | 25.9 °C | 119.38 mm |
| July | 17.6 °C | 28.7 °C | 102.62 mm |
| August | 16.8 °C | 27.6 °C | 119.13 mm |
| September | 12.8 °C | 23.8 °C | 121.16 mm |
| October | 6.4 °C | 17.4 °C | 118.11 mm |
| November | 1.1 °C | 11.3 °C | 105.41 mm |
| December | -3.3 °C | 5.4 °C | 114.3 mm |
| Annual | 5.4 °C | 16 °C | 1286.77 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |