Shelbyville, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 43.5 °F (low) to 63.7 °F (high). Annual precipitation averages 41.1 Inches. 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 | 19.9 °F | 35.9 °F | 2.52 in. |
| February | 23.0 °F | 40.9 °F | 2.07 in. |
| March | 32.2 °F | 51.9 °F | 2.88 in. |
| April | 42.6 °F | 64.6 °F | 4.55 in. |
| May | 53.9 °F | 74.7 °F | 4.7 in. |
| June | 62.9 °F | 83.4 °F | 4.73 in. |
| July | 65.8 °F | 86.5 °F | 3.92 in. |
| August | 63.6 °F | 85.5 °F | 3.14 in. |
| September | 55.5 °F | 80.3 °F | 3.01 in. |
| October | 44.2 °F | 67.7 °F | 3.45 in. |
| November | 33.5 °F | 52.5 °F | 3.51 in. |
| December | 25.3 °F | 40.8 °F | 2.6 in. |
| Annual | 43.5 °F | 63.7 °F | 41.08 in. |
| 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 : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |