Chestnut, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 42.3 °F (low) to 62.8 °F (high). Annual precipitation averages 38.5 Inches. Chestnut 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 18.1 °F | 34.6 °F | 2.23 in. |
| February | 21.3 °F | 39.5 °F | 2.05 in. |
| March | 30.5 °F | 51.0 °F | 2.73 in. |
| April | 41.3 °F | 64.1 °F | 3.97 in. |
| May | 52.8 °F | 74.3 °F | 4.33 in. |
| June | 62.1 °F | 83.1 °F | 4.42 in. |
| July | 65.0 °F | 85.9 °F | 4.17 in. |
| August | 63.0 °F | 84.2 °F | 3.25 in. |
| September | 54.7 °F | 79.3 °F | 3.0 in. |
| October | 43.1 °F | 66.6 °F | 3.22 in. |
| November | 32.3 °F | 51.7 °F | 2.9 in. |
| December | 23.7 °F | 39.5 °F | 2.27 in. |
| Annual | 42.3 °F | 62.8 °F | 38.54 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| 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 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |