Illinois planting zones & frost dates
The 14 Illinois cities on this site fall in zones 5b, 6a. Last spring frost dates range from Apr 17 in Chicago to May 6 in Schaumburg.
| City | Zone | Last frost | First frost | Population |
|---|---|---|---|---|
| Chicago | 6a | Apr 17 | Nov 1 | 2,721,308 |
| Aurora | 5b | Apr 25 | Oct 18 | 180,710 |
| Naperville | 5b | May 4 | Oct 11 | 153,124 |
| Joliet | 6a | Apr 26 | Oct 20 | 151,837 |
| Rockford | 5b | Apr 30 | Oct 12 | 147,486 |
| Elgin | 5b | May 1 | Oct 12 | 114,701 |
| Springfield | 6a | Apr 20 | Oct 17 | 112,949 |
| Peoria | 6a | Apr 23 | Oct 18 | 111,696 |
| Champaign | 6a | Apr 21 | Oct 19 | 91,961 |
| Waukegan | 6a | May 4 | Oct 12 | 88,570 |
| Cicero | 6a | Apr 17 | Oct 26 | 82,090 |
| Bloomington | 6a | May 1 | Oct 11 | 79,232 |
| Schaumburg | 5b | May 6 | Oct 8 | 77,099 |
| Evanston | 6a | May 2 | Oct 14 | 76,006 |
Frost dates are 30%-risk dates from the nearest suitable NOAA station. Population: Census Vintage 2024 estimates.