Illinois frost dates
The typical last spring frost ranges from Apr 11 in Chicago to Apr 26 in Elgin.
9 of the 9 Illinois cities listed have typical frost dates. The longest frost-free season is 201 days in Chicago; the shortest is 172 days in Galena. For a single address, look up your ZIP code: rural ZIPs use their nearest suitable station.
| City | Last spring frost | 1 in 10 after | First fall frost | 1 in 10 before | Hard freeze (28°F) | Season |
|---|---|---|---|---|---|---|
| Aurora | Apr 19 | May 4 | Oct 23 | Oct 9 | Apr 8 / Nov 2 | 185 days |
| Chicago | Apr 11 | Apr 27 | Oct 31 | Oct 20 | Apr 1 / Nov 11 | 201 days |
| Elgin | Apr 26 | May 12 | Oct 18 | Oct 3 | Apr 14 / Oct 29 | 174 days |
| Galena | Apr 25 | May 11 | Oct 16 | Oct 1 | Apr 13 / Oct 27 | 172 days |
| Joliet | Apr 19 | May 7 | Oct 25 | Oct 12 | Apr 5 / Nov 4 | 188 days |
| Naperville | Apr 19 | May 4 | Oct 23 | Oct 9 | Apr 8 / Nov 2 | 185 days |
| Peoria | Apr 16 | May 4 | Oct 23 | Oct 9 | Apr 5 / Nov 2 | 189 days |
| Rockford | Apr 24 | May 8 | Oct 17 | Oct 2 | Apr 13 / Oct 28 | 174 days |
| Springfield | Apr 14 | Apr 29 | Oct 20 | Oct 5 | Apr 3 / Oct 30 | 187 days |
Reading the table: Joliet
In Joliet, the last spring frost typically comes around Apr 19: in half of years it is earlier, in half later. In 1 year in 10 it comes after May 7, 18 days later, so tender plants set out after that date have a 90% chance of escaping frost. In fall, the first frost typically arrives around Oct 25, and in 1 year in 10 before Oct 12. Hard freezes (28°F) usually end earlier in spring and start later in fall: around Apr 5 and Nov 4 in Joliet.
Frost dates at more Illinois weather stations
NOAA stations across Illinois used by our ZIP code lookup, named for the town they are in.
| Station | Elevation | Last spring frost | First fall frost |
|---|---|---|---|
| Aledo | 730 ft | Apr 22 (1 in 10 after May 6) | Oct 19 (before Oct 6) |
| Alton - Melvin Price L&D | 405 ft | Apr 4 (1 in 10 after Apr 19) | Nov 5 (before Oct 25) |
| Belleville Siu Rsch | 450 ft | Apr 12 (1 in 10 after Apr 28) | Oct 20 (before Oct 3) |
| Bentley | 650 ft | Apr 13 (1 in 10 after Apr 30) | Oct 22 (before Oct 8) |
| Benton 2 N | 445 ft | Apr 4 (1 in 10 after Apr 21) | Oct 28 (before Oct 15) |
| Cahokia St Louis Airport | 413 ft | Apr 8 (1 in 10 after Apr 23) | Oct 26 (before Oct 12) |
| Cairo 3N | 313 ft | Apr 2 (1 in 10 after Apr 17) | Oct 31 (before Oct 18) |
| Carbondale Sewage Plt | 390 ft | Apr 9 (1 in 10 after Apr 25) | Oct 22 (before Oct 10) |
| Carlyle Rsvr | 501 ft | Apr 6 (1 in 10 after Apr 22) | Oct 29 (before Oct 16) |
| Carmi 3 | 335 ft | Apr 15 (1 in 10 after May 2) | Oct 19 (before Oct 4) |
| Champaign 9 Sw | 700 ft | Apr 23 (1 in 10 after May 9) | Oct 13 (before Sep 28) |
| Chicago Aurora Muni Airport | 710 ft | Apr 28 (1 in 10 after May 11) | Oct 13 (before Sep 27) |
| Chicago Botanic Garden | 630 ft | Apr 26 (1 in 10 after May 11) | Oct 21 (before Oct 5) |
| Chicago Midway Airport 3SW | 620 ft | Apr 10 (1 in 10 after Apr 26) | Nov 1 (before Oct 21) |
| Chicago Ohare Intl Airport | 658 ft | Apr 16 (1 in 10 after May 1) | Oct 28 (before Oct 15) |
| Chicago Waukegan Rgnl Airport | 727 ft | Apr 30 (1 in 10 after May 16) | Oct 21 (before Oct 5) |
| Congerville 2NW | 640 ft | Apr 21 (1 in 10 after May 7) | Oct 17 (before Oct 3) |
| Danville | 555 ft | Apr 21 (1 in 10 after May 7) | Oct 20 (before Oct 6) |
| De Kalb | 873 ft | Apr 24 (1 in 10 after May 10) | Oct 18 (before Oct 4) |
| Decatur Airport | 675 ft | Apr 16 (1 in 10 after Apr 30) | Oct 22 (before Oct 7) |
| Decatur WTP | 639 ft | Apr 14 (1 in 10 after May 1) | Oct 24 (before Oct 11) |
| Dixon Springs Agric Ctr | 527 ft | Apr 14 (1 in 10 after Apr 30) | Oct 21 (before Oct 6) |
| Du Quoin 4 Se | 420 ft | Apr 6 (1 in 10 after Apr 22) | Oct 22 (before Oct 9) |
| Dwight | 628 ft | Apr 27 (1 in 10 after May 14) | Oct 15 (before Sep 30) |
| Effingham 3SW | 625 ft | Apr 13 (1 in 10 after Apr 29) | Oct 24 (before Oct 9) |
| Fairfield Radio Wfiw | 430 ft | Apr 7 (1 in 10 after Apr 23) | Oct 26 (before Oct 14) |
| Freeport Waste WTP | 750 ft | Apr 26 (1 in 10 after May 11) | Oct 13 (before Sep 30) |
| Galesburg | 761 ft | Apr 20 (1 in 10 after May 5) | Oct 19 (before Oct 4) |
| Galva | 810 ft | Apr 26 (1 in 10 after May 11) | Oct 12 (before Sep 25) |
| Harrisburg | 365 ft | Apr 7 (1 in 10 after Apr 25) | Oct 26 (before Oct 10) |
| Havana | 463 ft | Apr 17 (1 in 10 after May 3) | Oct 19 (before Oct 1) |
| Hillsboro | 630 ft | Apr 13 (1 in 10 after Apr 28) | Oct 24 (before Oct 10) |
| Hoopeston | 710 ft | Apr 22 (1 in 10 after May 8) | Oct 19 (before Oct 5) |
| Jacksonville 2E | 610 ft | Apr 19 (1 in 10 after May 5) | Oct 17 (before Oct 1) |
| Jerseyville 2 Sw | 630 ft | Apr 14 (1 in 10 after Apr 30) | Oct 19 (before Oct 7) |
| Kankakee Metro Wastewater | 600 ft | Apr 19 (1 in 10 after May 3) | Oct 24 (before Oct 12) |
| Lincoln | 583 ft | Apr 20 (1 in 10 after May 4) | Oct 16 (before Oct 3) |
| Mc Henry -Wg Stratton L&D | 736 ft | May 1 (1 in 10 after May 19) | Oct 11 (before Sep 27) |
| Minonk | 750 ft | Apr 26 (1 in 10 after May 10) | Oct 17 (before Oct 1) |
| Moline Quad City Intl Airport | 592 ft | Apr 24 (1 in 10 after May 9) | Oct 18 (before Oct 4) |
| Morrisonville | 630 ft | Apr 12 (1 in 10 after Apr 27) | Oct 20 (before Oct 5) |
| Mt Vernon 3 Ne | 490 ft | Apr 11 (1 in 10 after Apr 26) | Oct 22 (before Oct 9) |
| Nashville 1 E | 513 ft | Apr 7 (1 in 10 after Apr 22) | Oct 26 (before Oct 14) |
| Normal 4NE | 790 ft | Apr 25 (1 in 10 after May 11) | Oct 16 (before Oct 2) |
| Paris Stp | 649 ft | Apr 21 (1 in 10 after May 9) | Oct 20 (before Oct 1) |
| Park Forest | 710 ft | Apr 23 (1 in 10 after May 11) | Oct 20 (before Oct 6) |
| Peru | 620 ft | Apr 24 (1 in 10 after May 8) | Oct 18 (before Oct 3) |
| Prairie City 2S | 650 ft | Apr 17 (1 in 10 after May 2) | Oct 22 (before Oct 7) |
| Princeton | 697 ft | Apr 22 (1 in 10 after May 7) | Oct 17 (before Oct 3) |
| Quincy Rgnl Airport | 769 ft | Apr 14 (1 in 10 after May 1) | Oct 23 (before Oct 10) |
| Rantoul | 740 ft | Apr 21 (1 in 10 after May 6) | Oct 18 (before Oct 5) |
| Rushville | 673 ft | Apr 16 (1 in 10 after May 3) | Oct 23 (before Oct 10) |
| Smithland L&D | 357 ft | Apr 3 (1 in 10 after Apr 21) | Oct 30 (before Oct 17) |
| Sparta 1 W | 535 ft | Apr 12 (1 in 10 after Apr 29) | Oct 22 (before Oct 7) |
| Stockton 3 Nne | 970 ft | Apr 27 (1 in 10 after May 12) | Oct 9 (before Sep 26) |
| Tuscola | 651 ft | Apr 15 (1 in 10 after May 1) | Oct 20 (before Oct 7) |
| Walnut | 671 ft | Apr 24 (1 in 10 after May 9) | Oct 14 (before Sep 30) |
| Watseka 2 Nw | 620 ft | Apr 24 (1 in 10 after May 10) | Oct 16 (before Oct 1) |
| West Chicago Dupage Airport | 754 ft | Apr 25 (1 in 10 after May 12) | Oct 19 (before Oct 5) |
| White Hall 1 E | 580 ft | Apr 13 (1 in 10 after Apr 28) | Oct 22 (before Oct 9) |
32°F dates from NOAA 1991-2020 freeze probabilities for each city's station. "1 in 10 after": a 10% chance of a later spring frost (planting is 90% safe after it). How to read frost dates.