Plattville, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.7 °C (low) to 15.6 °C (high). Annual precipitation averages 979.9 Millimeters. Plattville is located in USDA Plant Hardiness Zone 5b. 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 | -9.1 °C | -0.3 °C | 48.26 mm |
| February | -7.5 °C | 1.8 °C | 43.69 mm |
| March | -2.2 °C | 8.5 °C | 60.71 mm |
| April | 3.7 °C | 15.8 °C | 97.03 mm |
| May | 10 °C | 22 °C | 122.43 mm |
| June | 15.6 °C | 27.2 °C | 117.86 mm |
| July | 17.6 °C | 29 °C | 104.14 mm |
| August | 16.7 °C | 27.9 °C | 99.57 mm |
| September | 12.2 °C | 25 °C | 84.58 mm |
| October | 5.6 °C | 17.7 °C | 83.06 mm |
| November | -0.3 °C | 9.5 °C | 63.75 mm |
| December | -5.8 °C | 2.5 °C | 54.86 mm |
| Annual | 4.7 °C | 15.6 °C | 979.94 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°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 |