Carterville, Illinois has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 46.1 °F (low) to 66.6 °F (high). Annual precipitation averages 47.9 Inches. Carterville is located in USDA Plant Hardiness Zone 7a. 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 | 24.0 °F | 41.0 °F | 3.38 in. |
| February | 27.2 °F | 46.1 °F | 3.1 in. |
| March | 35.5 °F | 56.0 °F | 4.32 in. |
| April | 45.6 °F | 67.5 °F | 5.38 in. |
| May | 56.0 °F | 76.3 °F | 5.29 in. |
| June | 64.5 °F | 85.0 °F | 4.59 in. |
| July | 68.1 °F | 87.8 °F | 3.89 in. |
| August | 65.5 °F | 87.1 °F | 3.12 in. |
| September | 57.3 °F | 81.3 °F | 3.25 in. |
| October | 45.7 °F | 69.9 °F | 3.62 in. |
| November | 35.9 °F | 56.3 °F | 4.28 in. |
| December | 27.9 °F | 45.2 °F | 3.63 in. |
| Annual | 46.1 °F | 66.6 °F | 47.85 in. |
| 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 7a : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |