Lostant, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.9 °C (low) to 15.9 °C (high). Annual precipitation averages 947.2 Millimeters. Lostant is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.2 °C | -0.3 °C | 48.51 mm |
| February | -7.3 °C | 2.2 °C | 45.97 mm |
| March | -1.9 °C | 9.1 °C | 63.25 mm |
| April | 3.9 °C | 16.5 °C | 90.93 mm |
| May | 10.6 °C | 22.7 °C | 116.59 mm |
| June | 15.9 °C | 27.6 °C | 109.47 mm |
| July | 17.9 °C | 29.2 °C | 98.55 mm |
| August | 16.8 °C | 28.2 °C | 94.23 mm |
| September | 12.2 °C | 25.3 °C | 86.87 mm |
| October | 5.7 °C | 18.3 °C | 75.95 mm |
| November | -0.5 °C | 9.7 °C | 65.53 mm |
| December | -5.9 °C | 2.6 °C | 51.31 mm |
| Annual | 4.9 °C | 15.9 °C | 947.16 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |