Wilton, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 40.5 °F (low) to 59.9 °F (high). Annual precipitation averages 37.9 Inches. 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 | 14.0 °F | 30.2 °F | 1.37 in. |
| February | 17.5 °F | 34.7 °F | 1.64 in. |
| March | 28.4 °F | 47.6 °F | 2.4 in. |
| April | 39.5 °F | 61.2 °F | 3.68 in. |
| May | 51.4 °F | 72.1 °F | 4.81 in. |
| June | 61.3 °F | 81.4 °F | 5.13 in. |
| July | 64.8 °F | 84.5 °F | 4.26 in. |
| August | 62.5 °F | 82.7 °F | 4.07 in. |
| September | 54.2 °F | 76.8 °F | 3.59 in. |
| October | 42.3 °F | 63.8 °F | 2.92 in. |
| November | 30.5 °F | 48.8 °F | 2.2 in. |
| December | 20.0 °F | 35.5 °F | 1.84 in. |
| Annual | 40.5 °F | 59.9 °F | 37.91 in. |
| 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 : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |