Pearl City, Illinois has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.2 °C (low) to 14.5 °C (high). Annual precipitation averages 969.3 Millimeters. Pearl City is located in USDA Plant Hardiness Zone 5a. 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 | -11.4 °C | -1.9 °C | 38.35 mm |
| February | -9.4 °C | 0.4 °C | 42.42 mm |
| March | -3.5 °C | 7.3 °C | 55.12 mm |
| April | 2.4 °C | 14.9 °C | 95 mm |
| May | 8.9 °C | 21.3 °C | 112.52 mm |
| June | 14.6 °C | 26.6 °C | 137.41 mm |
| July | 16.4 °C | 28.2 °C | 114.55 mm |
| August | 15.2 °C | 27.3 °C | 99.82 mm |
| September | 10.5 °C | 23.8 °C | 95.76 mm |
| October | 4.2 °C | 16.7 °C | 73.41 mm |
| November | -1.9 °C | 8.1 °C | 57.4 mm |
| December | -7.8 °C | 1 °C | 47.5 mm |
| Annual | 3.2 °C | 14.5 °C | 969.26 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 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |