Sesser, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 7.8 °C (low) to 18.9 °C (high). Annual precipitation averages 1168.9 Millimeters. Sesser is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -4.8 °C | 4.4 °C | 78.23 mm |
| February | -3.1 °C | 7.2 °C | 71.12 mm |
| March | 1.8 °C | 12.8 °C | 100.84 mm |
| April | 7.5 °C | 19.6 °C | 130.56 mm |
| May | 13.3 °C | 24.6 °C | 131.83 mm |
| June | 18.1 °C | 29.4 °C | 122.43 mm |
| July | 20 °C | 30.8 °C | 101.85 mm |
| August | 18.7 °C | 30.3 °C | 79.5 mm |
| September | 14.2 °C | 27 °C | 81.28 mm |
| October | 7.8 °C | 20.7 °C | 85.09 mm |
| November | 2.1 °C | 13.1 °C | 104.39 mm |
| December | -2.5 °C | 6.8 °C | 81.79 mm |
| Annual | 7.8 °C | 18.9 °C | 1168.91 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |