Ridgway, Illinois has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 8.1 °C (low) to 19.4 °C (high). Annual precipitation averages 1194.6 Millimeters. Ridgway 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 | -3.8 °C | 5.2 °C | 91.44 mm |
| February | -2.3 °C | 7.9 °C | 81.28 mm |
| March | 2.1 °C | 13.3 °C | 113.54 mm |
| April | 7.7 °C | 19.9 °C | 124.97 mm |
| May | 13.6 °C | 24.9 °C | 129.79 mm |
| June | 18.3 °C | 29.5 °C | 111 mm |
| July | 20 °C | 31.1 °C | 103.38 mm |
| August | 18.7 °C | 30.6 °C | 76.2 mm |
| September | 14.6 °C | 27.8 °C | 79.76 mm |
| October | 8.1 °C | 21.2 °C | 84.84 mm |
| November | 2.3 °C | 13.6 °C | 101.6 mm |
| December | -1.8 °C | 7.6 °C | 96.77 mm |
| Annual | 8.1 °C | 19.4 °C | 1194.57 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 |