Rosiclare, Illinois has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 8.3 °C (low) to 19.6 °C (high). Annual precipitation averages 1248.9 Millimeters. Rosiclare is located in USDA Plant Hardiness Zone 7a. 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 | -3.6 °C | 5.7 °C | 96.77 mm |
| February | -2.1 °C | 8.4 °C | 89.92 mm |
| March | 2.4 °C | 13.8 °C | 118.62 mm |
| April | 7.8 °C | 20.1 °C | 131.57 mm |
| May | 13.5 °C | 24.9 °C | 136.14 mm |
| June | 18.2 °C | 29.5 °C | 113.54 mm |
| July | 20.3 °C | 31.2 °C | 108.46 mm |
| August | 19.1 °C | 30.7 °C | 77.47 mm |
| September | 14.9 °C | 27.6 °C | 80.52 mm |
| October | 8.3 °C | 21.3 °C | 86.61 mm |
| November | 2.4 °C | 13.9 °C | 103.38 mm |
| December | -1.8 °C | 7.8 °C | 105.92 mm |
| Annual | 8.3 °C | 19.6 °C | 1248.92 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| 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 |