Milan, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 41.6 °F (low) to 60.5 °F (high). Annual precipitation averages 37.9 Inches. 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 | 15.0 °F | 30.9 °F | 1.53 in. |
| February | 18.6 °F | 35.4 °F | 1.73 in. |
| March | 29.2 °F | 48.3 °F | 2.49 in. |
| April | 40.4 °F | 61.5 °F | 3.66 in. |
| May | 52.2 °F | 72.7 °F | 4.83 in. |
| June | 62.2 °F | 82.0 °F | 4.8 in. |
| July | 65.9 °F | 85.1 °F | 4.2 in. |
| August | 63.8 °F | 83.2 °F | 4.0 in. |
| September | 55.5 °F | 77.3 °F | 3.46 in. |
| October | 43.7 °F | 64.5 °F | 2.86 in. |
| November | 31.6 °F | 49.3 °F | 2.3 in. |
| December | 21.1 °F | 36.3 °F | 1.99 in. |
| Annual | 41.6 °F | 60.5 °F | 37.85 in. |
| 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 : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |