Wilton, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.7 °C (low) to 15.5 °C (high). Annual precipitation averages 962.9 Millimeters. Wilton is located in USDA Plant Hardiness Zone 5b. 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 | -10 °C | -1 °C | 34.8 mm |
| February | -8.1 °C | 1.5 °C | 41.66 mm |
| March | -2 °C | 8.7 °C | 60.96 mm |
| April | 4.2 °C | 16.2 °C | 93.47 mm |
| May | 10.8 °C | 22.3 °C | 122.17 mm |
| June | 16.3 °C | 27.4 °C | 130.3 mm |
| July | 18.2 °C | 29.2 °C | 108.2 mm |
| August | 16.9 °C | 28.2 °C | 103.38 mm |
| September | 12.3 °C | 24.9 °C | 91.19 mm |
| October | 5.7 °C | 17.7 °C | 74.17 mm |
| November | -0.8 °C | 9.3 °C | 55.88 mm |
| December | -6.7 °C | 1.9 °C | 46.74 mm |
| Annual | 4.7 °C | 15.5 °C | 962.92 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |