South Holland, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 41.9 °F (low) to 59.6 °F (high). Annual precipitation averages 39.8 Inches. South Holland is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 17.6 °F | 32.2 °F | 2.21 in. |
| February | 20.2 °F | 35.9 °F | 2.1 in. |
| March | 29.4 °F | 46.3 °F | 2.38 in. |
| April | 39.6 °F | 59.2 °F | 3.88 in. |
| May | 50.5 °F | 69.9 °F | 4.43 in. |
| June | 60.5 °F | 79.8 °F | 4.62 in. |
| July | 65.3 °F | 83.8 °F | 4.35 in. |
| August | 63.5 °F | 82.0 °F | 4.13 in. |
| September | 56.0 °F | 76.1 °F | 3.24 in. |
| October | 43.9 °F | 63.3 °F | 3.49 in. |
| November | 33.2 °F | 49.4 °F | 2.72 in. |
| December | 23.1 °F | 37.3 °F | 2.29 in. |
| Annual | 41.9 °F | 59.6 °F | 39.84 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |