Sims, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 7.5 °C (low) to 18.8 °C (high). Annual precipitation averages 1137.4 Millimeters. Sims 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 | 4.2 °C | 82.8 mm |
| February | -3.2 °C | 6.9 °C | 69.6 mm |
| March | 1.4 °C | 12.6 °C | 96.01 mm |
| April | 7.2 °C | 19.2 °C | 119.89 mm |
| May | 13.1 °C | 24.5 °C | 121.16 mm |
| June | 17.8 °C | 29.4 °C | 122.94 mm |
| July | 19.5 °C | 30.8 °C | 97.03 mm |
| August | 18.2 °C | 30.3 °C | 85.34 mm |
| September | 13.7 °C | 27.2 °C | 80.01 mm |
| October | 7.4 °C | 20.8 °C | 86.61 mm |
| November | 1.7 °C | 12.8 °C | 97.28 mm |
| December | -2.5 °C | 6.6 °C | 78.74 mm |
| Annual | 7.5 °C | 18.8 °C | 1137.41 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 | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |