Cornell, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5 °C (low) to 16.1 °C (high). Annual precipitation averages 956.8 Millimeters. Cornell 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 | -8.9 °C | -0.1 °C | 52.07 mm |
| February | -7.1 °C | 2.4 °C | 46.23 mm |
| March | -1.7 °C | 9.3 °C | 65.53 mm |
| April | 4.2 °C | 16.8 °C | 91.19 mm |
| May | 10.7 °C | 22.9 °C | 115.57 mm |
| June | 16 °C | 27.7 °C | 108.46 mm |
| July | 17.9 °C | 29.2 °C | 100.84 mm |
| August | 16.7 °C | 28.2 °C | 91.95 mm |
| September | 12.2 °C | 25.4 °C | 85.6 mm |
| October | 5.8 °C | 18.4 °C | 78.99 mm |
| November | -0.2 °C | 9.8 °C | 67.31 mm |
| December | -5.7 °C | 2.8 °C | 53.09 mm |
| Annual | 5 °C | 16.1 °C | 956.83 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 |