Stonefort, Illinois has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 7.8 °C (low) to 19.3 °C (high). Annual precipitation averages 1277.1 Millimeters. Stonefort 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 | -4.2 °C | 5.3 °C | 97.79 mm |
| February | -2.6 °C | 7.9 °C | 85.6 mm |
| March | 1.9 °C | 13.4 °C | 118.87 mm |
| April | 7.4 °C | 20 °C | 144.02 mm |
| May | 13.3 °C | 24.7 °C | 140.46 mm |
| June | 17.9 °C | 29.2 °C | 120.14 mm |
| July | 19.9 °C | 30.9 °C | 99.31 mm |
| August | 18.6 °C | 30.6 °C | 75.69 mm |
| September | 14.2 °C | 27.4 °C | 85.34 mm |
| October | 7.7 °C | 21.4 °C | 93.47 mm |
| November | 2.1 °C | 13.7 °C | 111.51 mm |
| December | -2.2 °C | 7.5 °C | 104.9 mm |
| Annual | 7.8 °C | 19.3 °C | 1277.1 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 |