Rockwood, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 7.7 °C (low) to 19.4 °C (high). Annual precipitation averages 1140.2 Millimeters. Rockwood 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 | -4.6 °C | 5.2 °C | 72.9 mm |
| February | -2.5 °C | 8.1 °C | 69.34 mm |
| March | 1.7 °C | 13.6 °C | 97.28 mm |
| April | 7.3 °C | 19.9 °C | 128.52 mm |
| May | 13.2 °C | 24.9 °C | 135.13 mm |
| June | 18.2 °C | 29.7 °C | 111.76 mm |
| July | 20.1 °C | 31.3 °C | 99.57 mm |
| August | 18.8 °C | 31 °C | 77.98 mm |
| September | 13.8 °C | 27.4 °C | 81.53 mm |
| October | 7.3 °C | 21.3 °C | 83.82 mm |
| November | 2 °C | 13.6 °C | 102.11 mm |
| December | -2.6 °C | 7.2 °C | 80.26 mm |
| Annual | 7.7 °C | 19.4 °C | 1140.2 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 | Dfa - Humid Continental Hot Summers With Year Around Precipitation |