Chadwick, Illinois has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 37.9 °F (low) to 59 °F (high). Annual precipitation averages 38.7 Inches. Chadwick is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 11.9 °F | 29.2 °F | 1.61 in. |
| February | 15.6 °F | 33.7 °F | 1.77 in. |
| March | 26.1 °F | 46.0 °F | 2.33 in. |
| April | 36.7 °F | 59.9 °F | 3.79 in. |
| May | 48.4 °F | 71.5 °F | 4.6 in. |
| June | 58.4 °F | 80.8 °F | 5.23 in. |
| July | 61.7 °F | 83.7 °F | 4.71 in. |
| August | 59.4 °F | 82.2 °F | 4.02 in. |
| September | 50.9 °F | 76.0 °F | 3.65 in. |
| October | 39.5 °F | 63.1 °F | 2.82 in. |
| November | 28.5 °F | 47.4 °F | 2.26 in. |
| December | 18.2 °F | 34.6 °F | 1.95 in. |
| Annual | 37.9 °F | 59 °F | 38.74 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |