Eldorado, Illinois has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 46.1 °F (low) to 66.7 °F (high). Annual precipitation averages 47.2 Inches. Eldorado 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 | 24.7 °F | 41.2 °F | 3.7 in. |
| February | 27.4 °F | 46.1 °F | 3.13 in. |
| March | 35.4 °F | 55.9 °F | 4.29 in. |
| April | 45.3 °F | 67.8 °F | 5.01 in. |
| May | 55.9 °F | 76.5 °F | 5.19 in. |
| June | 64.4 °F | 84.6 °F | 4.63 in. |
| July | 67.6 °F | 87.7 °F | 3.94 in. |
| August | 65.2 °F | 87.0 °F | 2.97 in. |
| September | 57.6 °F | 81.6 °F | 3.15 in. |
| October | 45.8 °F | 70.1 °F | 3.41 in. |
| November | 35.8 °F | 56.4 °F | 4.08 in. |
| December | 28.2 °F | 45.3 °F | 3.73 in. |
| Annual | 46.1 °F | 66.7 °F | 47.23 in. |
| 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 : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |