Brussels, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 7.8 °C (low) to 18.7 °C (high). Annual precipitation averages 1057.1 Millimeters. Brussels 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. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -5.4 °C | 3.8 °C | 59.94 mm |
| February | -3.6 °C | 6.9 °C | 55.63 mm |
| March | 1.3 °C | 12.8 °C | 81.53 mm |
| April | 7.3 °C | 19.3 °C | 113.79 mm |
| May | 13.3 °C | 24.4 °C | 124.71 mm |
| June | 18.4 °C | 29.2 °C | 115.57 mm |
| July | 20.4 °C | 31.1 °C | 98.3 mm |
| August | 19.3 °C | 30.5 °C | 91.19 mm |
| September | 14.6 °C | 26.9 °C | 84.33 mm |
| October | 8.2 °C | 20.3 °C | 82.04 mm |
| November | 2.1 °C | 12.7 °C | 84.58 mm |
| December | -2.8 °C | 6.5 °C | 65.53 mm |
| Annual | 7.8 °C | 18.7 °C | 1057.14 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| 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 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |