Shelbyville, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6.4 °C (low) to 17.6 °C (high). Annual precipitation averages 1043.4 Millimeters. Shelbyville 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 | -6.7 °C | 2.2 °C | 64.01 mm |
| February | -5 °C | 4.9 °C | 52.58 mm |
| March | 0.1 °C | 11.1 °C | 73.15 mm |
| April | 5.9 °C | 18.1 °C | 115.57 mm |
| May | 12.2 °C | 23.7 °C | 119.38 mm |
| June | 17.2 °C | 28.6 °C | 120.14 mm |
| July | 18.8 °C | 30.3 °C | 99.57 mm |
| August | 17.6 °C | 29.7 °C | 79.76 mm |
| September | 13.1 °C | 26.8 °C | 76.45 mm |
| October | 6.8 °C | 19.8 °C | 87.63 mm |
| November | 0.8 °C | 11.4 °C | 89.15 mm |
| December | -3.7 °C | 4.9 °C | 66.04 mm |
| Annual | 6.4 °C | 17.6 °C | 1043.43 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 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |