Donovan, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.8 °C (low) to 16.2 °C (high). Annual precipitation averages 999.5 Millimeters. Donovan 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 | -8.7 °C | 0.2 °C | 56.13 mm |
| February | -7 °C | 2.8 °C | 49.78 mm |
| March | -1.7 °C | 9.2 °C | 63.75 mm |
| April | 3.8 °C | 16.7 °C | 96.01 mm |
| May | 10.3 °C | 22.8 °C | 109.98 mm |
| June | 15.7 °C | 27.7 °C | 125.98 mm |
| July | 17.4 °C | 29.1 °C | 116.84 mm |
| August | 16.2 °C | 28.3 °C | 91.95 mm |
| September | 11.7 °C | 25.6 °C | 80.77 mm |
| October | 5.5 °C | 18.6 °C | 83.82 mm |
| November | -0.3 °C | 10 °C | 67.31 mm |
| December | -5.6 °C | 3 °C | 57.15 mm |
| Annual | 4.8 °C | 16.2 °C | 999.47 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 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 |