Warsaw, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6.1 °C (low) to 16.9 °C (high). Annual precipitation averages 1023.9 Millimeters. Warsaw is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.1 °C | 1.1 °C | 42.93 mm |
| February | -6.2 °C | 3.7 °C | 47.5 mm |
| March | -0.6 °C | 10.4 °C | 65.53 mm |
| April | 5.5 °C | 17.4 °C | 103.12 mm |
| May | 11.8 °C | 23.1 °C | 138.43 mm |
| June | 17.3 °C | 28.1 °C | 129.29 mm |
| July | 19.3 °C | 30.2 °C | 107.44 mm |
| August | 18.2 °C | 29.3 °C | 95.76 mm |
| September | 13.5 °C | 25.7 °C | 92.96 mm |
| October | 6.9 °C | 18.8 °C | 83.57 mm |
| November | 0.5 °C | 10.7 °C | 67.31 mm |
| December | -5 °C | 3.8 °C | 50.04 mm |
| Annual | 6.1 °C | 16.9 °C | 1023.88 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |