Prairie City, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5 °C (low) to 16.5 °C (high). Annual precipitation averages 967.2 Millimeters. Prairie City 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 | -9.3 °C | 0.3 °C | 47.5 mm |
| February | -7.3 °C | 2.9 °C | 48.01 mm |
| March | -1.6 °C | 9.9 °C | 66.04 mm |
| April | 4.3 °C | 17.3 °C | 95 mm |
| May | 11 °C | 23.1 °C | 127 mm |
| June | 16.4 °C | 27.9 °C | 123.95 mm |
| July | 18.1 °C | 29.7 °C | 100.33 mm |
| August | 16.7 °C | 28.7 °C | 85.34 mm |
| September | 12.3 °C | 25.5 °C | 91.95 mm |
| October | 5.7 °C | 18.7 °C | 76.71 mm |
| November | -0.6 °C | 10.2 °C | 59.44 mm |
| December | -6 °C | 3.2 °C | 45.97 mm |
| Annual | 5 °C | 16.5 °C | 967.24 mm |
| 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 : -23.3°C to -20.6°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 |