Olympia Fields, 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 15.4 °C (high). Annual precipitation averages 1023.1 Millimeters. Olympia Fields 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 | -8.5 °C | -0.1 °C | 57.15 mm |
| February | -6.9 °C | 2.1 °C | 53.09 mm |
| March | -1.8 °C | 8.3 °C | 61.21 mm |
| April | 3.9 °C | 15.3 °C | 99.57 mm |
| May | 10 °C | 21.3 °C | 114.81 mm |
| June | 15.5 °C | 26.7 °C | 118.62 mm |
| July | 18.1 °C | 28.9 °C | 114.3 mm |
| August | 17.2 °C | 27.9 °C | 105.16 mm |
| September | 12.9 °C | 24.4 °C | 82.3 mm |
| October | 6.2 °C | 17.2 °C | 88.65 mm |
| November | 0.2 °C | 9.5 °C | 70.1 mm |
| December | -5.3 °C | 2.7 °C | 58.17 mm |
| Annual | 5.1 °C | 15.4 °C | 1023.13 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 |