Plattville, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 40.5 °F (low) to 60 °F (high). Annual precipitation averages 38.6 Inches. 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 | 15.7 °F | 31.4 °F | 1.9 in. |
| February | 18.5 °F | 35.3 °F | 1.72 in. |
| March | 28.1 °F | 47.3 °F | 2.39 in. |
| April | 38.7 °F | 60.5 °F | 3.82 in. |
| May | 50.0 °F | 71.6 °F | 4.82 in. |
| June | 60.0 °F | 81.0 °F | 4.64 in. |
| July | 63.6 °F | 84.2 °F | 4.1 in. |
| August | 62.0 °F | 82.3 °F | 3.92 in. |
| September | 53.9 °F | 77.0 °F | 3.33 in. |
| October | 42.0 °F | 63.9 °F | 3.27 in. |
| November | 31.4 °F | 49.1 °F | 2.51 in. |
| December | 21.5 °F | 36.5 °F | 2.16 in. |
| Annual | 40.5 °F | 60 °F | 38.58 in. |
| 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 : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |