Zion, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.9 °C (low) to 13.4 °C (high). Annual precipitation averages 932.2 Millimeters. Zion is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.8 °C | -0.9 °C | 49.28 mm |
| February | -7.3 °C | 0.8 °C | 50.55 mm |
| March | -2.3 °C | 6 °C | 57.15 mm |
| April | 3.2 °C | 11.8 °C | 99.06 mm |
| May | 8.8 °C | 17.9 °C | 108.71 mm |
| June | 14.4 °C | 23.5 °C | 105.92 mm |
| July | 17.9 °C | 26.7 °C | 89.15 mm |
| August | 17.7 °C | 26 °C | 90.17 mm |
| September | 13.4 °C | 22.4 °C | 86.61 mm |
| October | 6.8 °C | 15.7 °C | 81.03 mm |
| November | 0.3 °C | 8.5 °C | 61.21 mm |
| December | -5.4 °C | 2.1 °C | 53.34 mm |
| Annual | 4.9 °C | 13.4 °C | 932.18 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |