Prairie Grove, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 3.8 °C (low) to 14.5 °C (high). Annual precipitation averages 976.4 Millimeters. Prairie Grove 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 | -10.1 °C | -1.4 °C | 46.23 mm |
| February | -8.6 °C | 0.7 °C | 47.5 mm |
| March | -3.3 °C | 7.1 °C | 56.13 mm |
| April | 2.6 °C | 14.4 °C | 95.25 mm |
| May | 8.6 °C | 20.8 °C | 121.67 mm |
| June | 14.2 °C | 26.2 °C | 125.98 mm |
| July | 16.9 °C | 28.4 °C | 100.84 mm |
| August | 16 °C | 27.4 °C | 100.08 mm |
| September | 11.6 °C | 23.7 °C | 89.92 mm |
| October | 4.9 °C | 16.4 °C | 80.01 mm |
| November | -1 °C | 8.4 °C | 61.47 mm |
| December | -6.7 °C | 1.6 °C | 51.31 mm |
| Annual | 3.8 °C | 14.5 °C | 976.39 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 |