Carmi, Illinois has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 7.7 °C (low) to 19.2 °C (high). Annual precipitation averages 1183.9 Millimeters. Carmi 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 | -4.3 °C | 4.7 °C | 87.38 mm |
| February | -2.8 °C | 7.6 °C | 74.42 mm |
| March | 1.7 °C | 13 °C | 104.65 mm |
| April | 7.4 °C | 19.7 °C | 126.49 mm |
| May | 13.3 °C | 24.8 °C | 133.6 mm |
| June | 18.1 °C | 29.7 °C | 111.51 mm |
| July | 19.7 °C | 31 °C | 104.9 mm |
| August | 18.4 °C | 30.4 °C | 79.5 mm |
| September | 14 °C | 27.6 °C | 81.53 mm |
| October | 7.6 °C | 21.2 °C | 86.87 mm |
| November | 1.9 °C | 13.3 °C | 100.84 mm |
| December | -2.2 °C | 7.2 °C | 92.2 mm |
| Annual | 7.7 °C | 19.2 °C | 1183.89 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |