Du Bois, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 7.6 °C (low) to 18.6 °C (high). Annual precipitation averages 1155.7 Millimeters. Du Bois is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -5.1 °C | 4.1 °C | 75.18 mm |
| February | -3.3 °C | 6.8 °C | 67.82 mm |
| March | 1.6 °C | 12.5 °C | 97.28 mm |
| April | 7.3 °C | 19.1 °C | 124.97 mm |
| May | 13.2 °C | 24.2 °C | 130.05 mm |
| June | 18 °C | 29.2 °C | 123.44 mm |
| July | 19.8 °C | 30.8 °C | 105.16 mm |
| August | 18.6 °C | 30.3 °C | 82.3 mm |
| September | 14 °C | 26.9 °C | 84.07 mm |
| October | 7.7 °C | 20.6 °C | 85.34 mm |
| November | 1.9 °C | 12.7 °C | 101.85 mm |
| December | -2.7 °C | 6.3 °C | 78.23 mm |
| Annual | 7.6 °C | 18.6 °C | 1155.69 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |