Rossville, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.3 °C (low) to 16.5 °C (high). Annual precipitation averages 1006.9 Millimeters. Rossville is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.1 °C | 0.6 °C | 58.17 mm |
| February | -6.4 °C | 3.2 °C | 49.28 mm |
| March | -1.2 °C | 9.7 °C | 68.58 mm |
| April | 4.6 °C | 17.2 °C | 102.36 mm |
| May | 11.1 °C | 23.2 °C | 114.81 mm |
| June | 16.2 °C | 27.8 °C | 122.43 mm |
| July | 17.7 °C | 29.2 °C | 109.98 mm |
| August | 16.5 °C | 28.3 °C | 85.34 mm |
| September | 12.3 °C | 25.8 °C | 77.22 mm |
| October | 6 °C | 18.8 °C | 83.31 mm |
| November | 0.2 °C | 10.3 °C | 76.45 mm |
| December | -4.9 °C | 3.4 °C | 58.93 mm |
| Annual | 5.3 °C | 16.5 °C | 1006.86 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°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 |