Richton Park, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.1 °C (low) to 15.3 °C (high). Annual precipitation averages 1029.5 Millimeters. Richton Park 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 | -8.6 °C | -0.2 °C | 57.91 mm |
| February | -7 °C | 2 °C | 53.34 mm |
| March | -1.8 °C | 8.2 °C | 60.96 mm |
| April | 4.1 °C | 15.3 °C | 99.06 mm |
| May | 10 °C | 21.3 °C | 115.57 mm |
| June | 15.4 °C | 26.8 °C | 119.89 mm |
| July | 18.1 °C | 28.9 °C | 115.57 mm |
| August | 17.2 °C | 27.9 °C | 105.92 mm |
| September | 12.9 °C | 24.3 °C | 83.57 mm |
| October | 6.2 °C | 17.2 °C | 89.15 mm |
| November | 0.3 °C | 9.4 °C | 70.36 mm |
| December | -5.4 °C | 2.6 °C | 58.17 mm |
| Annual | 5.1 °C | 15.3 °C | 1029.47 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 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 |