Lake Summerset, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 37.9 °F (low) to 57.4 °F (high). Annual precipitation averages 37.4 Inches. Lake Summerset is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 11.7 °F | 27.9 °F | 1.57 in. |
| February | 15.0 °F | 32.0 °F | 1.6 in. |
| March | 25.5 °F | 44.3 °F | 2.09 in. |
| April | 36.3 °F | 57.9 °F | 3.69 in. |
| May | 48.1 °F | 69.5 °F | 4.23 in. |
| June | 58.2 °F | 79.3 °F | 5.36 in. |
| July | 61.7 °F | 82.4 °F | 3.99 in. |
| August | 59.8 °F | 80.8 °F | 3.99 in. |
| September | 51.4 °F | 74.2 °F | 3.75 in. |
| October | 39.9 °F | 61.3 °F | 2.93 in. |
| November | 28.8 °F | 46.1 °F | 2.31 in. |
| December | 18.3 °F | 33.4 °F | 1.87 in. |
| Annual | 37.9 °F | 57.4 °F | 37.38 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| 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 | Dfa - Humid Continental Hot Summers With Year Around Precipitation |