Illinois frost dates by city
| City | Last frost (50%) | Safer date (10%) | First frost (50%) | Season |
|---|---|---|---|---|
| Chicago | Apr 16 | May 1 | Oct 28 | 193 days |
| Peoria | Apr 16 | May 4 | Oct 23 | 189 days |
| Springfield | Apr 14 | Apr 29 | Oct 20 | 187 days |
Each city uses its nearest major NOAA weather station, usually the airport. Valleys, hilltops and rural spots can differ from it by one to three weeks. How to read these dates.