Polo, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 38.2 °F (low) to 59.1 °F (high). Annual precipitation averages 39.5 Inches. 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 | 12.6 °F | 29.4 °F | 1.8 in. |
| February | 15.9 °F | 33.7 °F | 1.85 in. |
| March | 26.4 °F | 46.2 °F | 2.43 in. |
| April | 36.7 °F | 60.1 °F | 3.84 in. |
| May | 48.5 °F | 71.6 °F | 4.74 in. |
| June | 58.4 °F | 80.7 °F | 5.21 in. |
| July | 61.6 °F | 83.5 °F | 4.56 in. |
| August | 59.5 °F | 82.1 °F | 3.95 in. |
| September | 51.1 °F | 76.3 °F | 3.69 in. |
| October | 39.9 °F | 63.2 °F | 2.91 in. |
| November | 28.9 °F | 47.7 °F | 2.4 in. |
| December | 18.7 °F | 34.7 °F | 2.14 in. |
| Annual | 38.2 °F | 59.1 °F | 39.52 in. |
| 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 : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |