Springfield, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6 °C (low) to 17.3 °C (high). Annual precipitation averages 977.2 Millimeters. Springfield is located in USDA Plant Hardiness Zone 6a. 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 | -7.4 °C | 1.8 °C | 55.12 mm |
| February | -5.6 °C | 4.4 °C | 49.53 mm |
| March | -0.5 °C | 10.9 °C | 70.36 mm |
| April | 5.4 °C | 17.9 °C | 101.35 mm |
| May | 11.8 °C | 23.6 °C | 119.38 mm |
| June | 16.9 °C | 28.3 °C | 118.36 mm |
| July | 18.6 °C | 30 °C | 91.44 mm |
| August | 17.4 °C | 29.2 °C | 80.01 mm |
| September | 12.8 °C | 26.3 °C | 81.79 mm |
| October | 6.4 °C | 19.4 °C | 77.98 mm |
| November | 0.4 °C | 11.2 °C | 74.93 mm |
| December | -4.4 °C | 4.6 °C | 56.9 mm |
| Annual | 6 °C | 17.3 °C | 977.15 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°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 |