Zion, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 40.8 °F (low) to 56.1 °F (high). Annual precipitation averages 36.7 Inches. 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 | 16.2 °F | 30.3 °F | 1.94 in. |
| February | 18.9 °F | 33.4 °F | 1.99 in. |
| March | 27.8 °F | 42.8 °F | 2.25 in. |
| April | 37.8 °F | 53.2 °F | 3.9 in. |
| May | 47.8 °F | 64.3 °F | 4.28 in. |
| June | 57.9 °F | 74.3 °F | 4.17 in. |
| July | 64.3 °F | 80.0 °F | 3.51 in. |
| August | 63.9 °F | 78.8 °F | 3.55 in. |
| September | 56.1 °F | 72.3 °F | 3.41 in. |
| October | 44.2 °F | 60.3 °F | 3.19 in. |
| November | 32.6 °F | 47.3 °F | 2.41 in. |
| December | 22.3 °F | 35.7 °F | 2.1 in. |
| Annual | 40.8 °F | 56.1 °F | 36.7 in. |
| 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 : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |