Milan, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.3 °C (low) to 15.9 °C (high). Annual precipitation averages 961.4 Millimeters. Milan is located in USDA Plant Hardiness Zone 5b. 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 | -9.4 °C | -0.6 °C | 38.86 mm |
| February | -7.4 °C | 1.9 °C | 43.94 mm |
| March | -1.6 °C | 9.1 °C | 63.25 mm |
| April | 4.7 °C | 16.4 °C | 92.96 mm |
| May | 11.2 °C | 22.6 °C | 122.68 mm |
| June | 16.8 °C | 27.8 °C | 121.92 mm |
| July | 18.8 °C | 29.5 °C | 106.68 mm |
| August | 17.7 °C | 28.4 °C | 101.6 mm |
| September | 13.1 °C | 25.2 °C | 87.88 mm |
| October | 6.5 °C | 18.1 °C | 72.64 mm |
| November | -0.2 °C | 9.6 °C | 58.42 mm |
| December | -6.1 °C | 2.4 °C | 50.55 mm |
| Annual | 5.3 °C | 15.9 °C | 961.38 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 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 |