Lacon, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 41.3 °F (low) to 61.7 °F (high). Annual precipitation averages 38 Inches. Lacon 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 | 16.2 °F | 32.4 °F | 2.08 in. |
| February | 19.6 °F | 36.8 °F | 1.91 in. |
| March | 29.5 °F | 49.3 °F | 2.6 in. |
| April | 40.0 °F | 62.9 °F | 3.86 in. |
| May | 51.4 °F | 73.7 °F | 4.8 in. |
| June | 61.0 °F | 82.6 °F | 4.15 in. |
| July | 64.6 °F | 85.7 °F | 3.81 in. |
| August | 62.6 °F | 84.3 °F | 3.61 in. |
| September | 54.3 °F | 78.5 °F | 3.4 in. |
| October | 42.7 °F | 65.8 °F | 3.13 in. |
| November | 31.7 °F | 50.5 °F | 2.62 in. |
| December | 22.0 °F | 37.6 °F | 2.06 in. |
| Annual | 41.3 °F | 61.7 °F | 38.03 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 125-150 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 |