Rockport, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6.4 °C (low) to 17.7 °C (high). Annual precipitation averages 979.4 Millimeters. Rockport is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -7.1 °C | 2.4 °C | 51.05 mm |
| February | -5.2 °C | 5.2 °C | 47.5 mm |
| March | 0 °C | 11.4 °C | 69.85 mm |
| April | 5.9 °C | 18.3 °C | 101.6 mm |
| May | 12.1 °C | 23.7 °C | 118.87 mm |
| June | 17.2 °C | 28.6 °C | 116.33 mm |
| July | 19.2 °C | 30.6 °C | 99.06 mm |
| August | 18.1 °C | 29.9 °C | 85.85 mm |
| September | 13.3 °C | 26.4 °C | 89.66 mm |
| October | 7 °C | 19.6 °C | 73.66 mm |
| November | 1 °C | 11.8 °C | 71.37 mm |
| December | -4.2 °C | 4.9 °C | 54.61 mm |
| Annual | 6.4 °C | 17.7 °C | 979.41 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |