Greenville, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 7 °C (low) to 18.1 °C (high). Annual precipitation averages 1087.1 Millimeters. Greenville 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 | -6 °C | 2.9 °C | 72.14 mm |
| February | -4 °C | 5.8 °C | 61.21 mm |
| March | 0.8 °C | 11.8 °C | 80.52 mm |
| April | 6.6 °C | 18.6 °C | 123.7 mm |
| May | 12.6 °C | 23.9 °C | 125.98 mm |
| June | 17.6 °C | 28.9 °C | 114.81 mm |
| July | 19.3 °C | 30.6 °C | 103.63 mm |
| August | 18 °C | 30.1 °C | 85.85 mm |
| September | 13.4 °C | 26.8 °C | 81.03 mm |
| October | 6.9 °C | 20.1 °C | 81.03 mm |
| November | 1.4 °C | 11.9 °C | 89.92 mm |
| December | -3.2 °C | 5.6 °C | 67.31 mm |
| Annual | 7 °C | 18.1 °C | 1087.13 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 100-125 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 |