Polo, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 3.4 °C (low) to 15.1 °C (high). Annual precipitation averages 1003.8 Millimeters. Polo 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. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -10.8 °C | -1.4 °C | 45.72 mm |
| February | -8.9 °C | 0.9 °C | 46.99 mm |
| March | -3.1 °C | 7.9 °C | 61.72 mm |
| April | 2.6 °C | 15.6 °C | 97.54 mm |
| May | 9.2 °C | 22 °C | 120.4 mm |
| June | 14.7 °C | 27.1 °C | 132.33 mm |
| July | 16.4 °C | 28.6 °C | 115.82 mm |
| August | 15.3 °C | 27.8 °C | 100.33 mm |
| September | 10.6 °C | 24.6 °C | 93.73 mm |
| October | 4.4 °C | 17.3 °C | 73.91 mm |
| November | -1.7 °C | 8.7 °C | 60.96 mm |
| December | -7.4 °C | 1.5 °C | 54.36 mm |
| Annual | 3.4 °C | 15.1 °C | 1003.81 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| 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 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |