Preemption, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.5 °C (low) to 15.3 °C (high). Annual precipitation averages 964.7 Millimeters. Preemption 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 | -10.2 °C | -1.2 °C | 39.62 mm |
| February | -8.2 °C | 1.3 °C | 45.72 mm |
| March | -2.3 °C | 8.7 °C | 61.72 mm |
| April | 3.8 °C | 16.2 °C | 95.25 mm |
| May | 10.4 °C | 22.1 °C | 124.46 mm |
| June | 15.9 °C | 27.1 °C | 122.17 mm |
| July | 18 °C | 28.8 °C | 103.38 mm |
| August | 16.8 °C | 27.8 °C | 98.55 mm |
| September | 12.2 °C | 24.4 °C | 91.95 mm |
| October | 5.7 °C | 17.3 °C | 72.9 mm |
| November | -1 °C | 9.1 °C | 58.67 mm |
| December | -6.8 °C | 1.8 °C | 50.29 mm |
| Annual | 4.5 °C | 15.3 °C | 964.68 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 |