Last frost dates in Illinois
170 NOAA weather stations in Illinois have thirty years of frost records. The median station sees its last 32 °F night around Apr 18; across the state that ranges from Apr 2 to May 2, so pick the station nearest you rather than a state-wide figure.
| CAIRO 3N | Apr 2 | Apr 17 | Mar 19 | Oct 31 | 211 |
| MT CARMEL | Apr 2 | Apr 17 | Mar 19 | Oct 31 | 209 |
| BROWNSTOWN 4 SW | Apr 3 | Apr 25 | Mar 19 | Oct 24 | 202 |
| GRAND CHAIN DAM 53 | Apr 3 | Apr 21 | Mar 17 | Nov 5 | 216 |
| SMITHLAND L&D | Apr 3 | Apr 21 | Mar 18 | Oct 30 | 207 |
| ALBION | Apr 4 | Apr 20 | Mar 20 | Oct 28 | 206 |
| ALTON - MELVIN PRICE L&D | Apr 4 | Apr 19 | Mar 18 | Nov 5 | 214 |
| BENTON 2 N | Apr 4 | Apr 21 | Mar 19 | Oct 28 | 206 |
| REND LAKE DAM | Apr 4 | Apr 19 | Mar 21 | Oct 27 | 204 |
| BROOKPORT DAM 52 | Apr 6 | Apr 23 | Mar 21 | Oct 27 | 203 |
| CAHOKIA | Apr 6 | Apr 20 | Mar 22 | Oct 27 | 203 |
| CARLYLE RSVR | Apr 6 | Apr 22 | Mar 23 | Oct 29 | 204 |
| DU QUOIN 4 SE | Apr 6 | Apr 22 | Mar 23 | Oct 22 | 199 |
| FAIRFIELD RADIO WFIW | Apr 7 | Apr 23 | Mar 23 | Oct 26 | 201 |
| GRAYVILLE | Apr 7 | Apr 23 | Mar 24 | Oct 25 | 201 |
| HARRISBURG | Apr 7 | Apr 25 | Mar 21 | Oct 26 | 202 |
| NASHVILLE 1 E | Apr 7 | Apr 22 | Mar 24 | Oct 26 | 201 |
| VIRDEN | Apr 7 | Apr 21 | Mar 22 | Oct 29 | 205 |
| ANNA 2 NNE | Apr 8 | Apr 26 | Mar 22 | Oct 29 | 203 |
| CAHOKIA ST LOUIS AP | Apr 8 | Apr 23 | Mar 23 | Oct 26 | 200 |
| GLADSTONE DAM 18 | Apr 8 | Apr 23 | Mar 26 | Oct 29 | 202 |
| KASKASKIA RVR NAVIGATION LOCK | Apr 8 | Apr 25 | Mar 22 | Oct 30 | 202 |
| LAWRENCEVILLE INTL AP | Apr 8 | Apr 22 | Mar 26 | Oct 26 | 200 |
| QUINCY DAM 21 | Apr 8 | Apr 23 | Mar 24 | Oct 30 | 204 |
| CARBONDALE SEWAGE PLT | Apr 9 | Apr 25 | Mar 25 | Oct 22 | 195 |
| CARBONDALE SOUTHERN IL AP | Apr 9 | Apr 25 | Mar 24 | Oct 22 | 195 |
| FLORA | Apr 9 | Apr 23 | Mar 29 | Oct 24 | 198 |
| IUKA 12 SW | Apr 9 | Apr 25 | Mar 27 | Oct 24 | 196 |
| SALEM | Apr 9 | Apr 23 | Mar 25 | Oct 26 | 197 |
| CHICAGO MIDWAY AP 3SW | Apr 10 | Apr 26 | Mar 30 | Nov 1 | 203 |
| CHICAGO NORTHERLY IS | Apr 10 | Apr 25 | Mar 29 | Nov 5 | 208 |
| FLORA 5 NW | Apr 10 | Apr 26 | Mar 26 | Oct 23 | 196 |
| SHELBYVILLE DAM | Apr 10 | Apr 28 | Mar 30 | Oct 24 | 195 |
| VANDALIA | Apr 10 | Apr 24 | Mar 28 | Oct 24 | 196 |
| CHICAGO MIDWAY AP | Apr 11 | Apr 27 | Mar 30 | Oct 31 | 201 |
| MATTOON | Apr 11 | Apr 28 | Mar 31 | Oct 29 | 199 |
| MCLEANSBORO | Apr 11 | Apr 26 | Mar 27 | Oct 21 | 190 |
| MT VERNON 3 NE | Apr 11 | Apr 26 | Mar 30 | Oct 22 | 193 |
| BELLEVILLE SIU RSCH | Apr 12 | Apr 28 | Mar 28 | Oct 20 | 189 |
| LAWRENCEVILLE 2WSW | Apr 12 | Apr 30 | Mar 31 | Oct 25 | 193 |
| MORRISONVILLE | Apr 12 | Apr 27 | Mar 29 | Oct 20 | 190 |
| PALESTINE | Apr 12 | Apr 26 | Mar 30 | Oct 22 | 193 |
| SPARTA 1 W | Apr 12 | Apr 29 | Mar 29 | Oct 22 | 191 |
| STREATOR 3 SE | Apr 12 | Apr 25 | Mar 30 | Oct 28 | 199 |
| BENTLEY | Apr 13 | Apr 30 | Mar 30 | Oct 22 | 191 |
| EFFINGHAM 3SW | Apr 13 | Apr 29 | Apr 1 | Oct 24 | 191 |
| FULTON L&D #13 | Apr 13 | Apr 28 | Apr 1 | Oct 26 | 195 |
| HILLSBORO | Apr 13 | Apr 28 | Mar 30 | Oct 24 | 192 |
| NEWTON | Apr 13 | Apr 29 | Apr 1 | Oct 22 | 190 |
| NEWTON 6 SSE | Apr 13 | Apr 27 | Mar 31 | Oct 22 | 191 |
| PETERSBURG 1E | Apr 13 | Apr 28 | Mar 31 | Oct 21 | 189 |
| ROBINSON | Apr 13 | Apr 28 | Apr 2 | Oct 22 | 190 |
| WHITE HALL 1 E | Apr 13 | Apr 28 | Mar 30 | Oct 22 | 190 |
| CARLINVILLE | Apr 14 | Apr 30 | Mar 31 | Oct 21 | 188 |
| CASEY | Apr 14 | Apr 30 | Apr 2 | Oct 20 | 187 |
| DECATUR WTP | Apr 14 | May 1 | Apr 1 | Oct 24 | 192 |
| DIXON SPRINGS AGRIC CTR | Apr 14 | Apr 30 | Mar 28 | Oct 21 | 189 |
| JERSEYVILLE 2 SW | Apr 14 | Apr 30 | Mar 31 | Oct 19 | 187 |
| NEW BOSTON DAM 17 | Apr 14 | May 2 | Apr 1 | Oct 24 | 190 |
| PITTSFIELD #2 | Apr 14 | Apr 30 | Mar 31 | Oct 21 | 189 |
| QUINCY RGNL AP | Apr 14 | May 1 | Mar 30 | Oct 23 | 191 |
| SPRINGFIELD CAPITAL AP | Apr 14 | Apr 29 | Apr 1 | Oct 20 | 187 |
| CARMI 3 | Apr 15 | May 2 | Apr 2 | Oct 19 | 183 |
| CHAMPAIGN 3S | Apr 15 | Apr 29 | Apr 1 | Oct 24 | 190 |
| CHARLESTON | Apr 15 | May 3 | Apr 1 | Oct 23 | 187 |
| MATTOON COLES CO AP | Apr 15 | Apr 30 | Apr 2 | Oct 24 | 189 |
| OLNEY 2S | Apr 15 | May 3 | Apr 1 | Oct 23 | 189 |
| RAMSEY | Apr 15 | May 1 | Apr 3 | Oct 19 | 185 |
| SPRINGFIELD #2 | Apr 15 | Apr 30 | Apr 3 | Oct 22 | 188 |
| SULLIVAN 3S | Apr 15 | Apr 30 | Apr 2 | Oct 22 | 187 |
| TUSCOLA | Apr 15 | May 1 | Apr 3 | Oct 20 | 188 |
| CHANNAHON DRESDEN ISL DAM | Apr 16 | May 3 | Apr 3 | Oct 26 | 191 |
| CHICAGO OHARE INTL AP | Apr 16 | May 1 | Apr 3 | Oct 28 | 193 |
| DECATUR AP | Apr 16 | Apr 30 | Apr 3 | Oct 22 | 187 |
| NEOGA 4NW | Apr 16 | Apr 29 | Apr 3 | Oct 20 | 185 |
| PEORIA GTR PEORIA AP | Apr 16 | May 4 | Apr 2 | Oct 23 | 189 |
| PONTIAC | Apr 16 | May 2 | Apr 3 | Oct 24 | 191 |
| RUSHVILLE | Apr 16 | May 3 | Apr 2 | Oct 23 | 189 |
| WINDSOR | Apr 16 | Apr 30 | Apr 3 | Oct 22 | 187 |
| HAVANA | Apr 17 | May 3 | Apr 2 | Oct 19 | 185 |
| JACKSONVILLE 2 | Apr 17 | May 1 | Apr 3 | Oct 21 | 186 |
| MASON CITY 4SE | Apr 17 | May 4 | Apr 4 | Oct 18 | 182 |
| PANA | Apr 17 | May 3 | Apr 4 | Oct 23 | 188 |
| PRAIRIE CITY 2S | Apr 17 | May 2 | Apr 4 | Oct 22 | 185 |
| GOLDEN | Apr 18 | May 1 | Apr 3 | Oct 21 | 187 |
| HENNEPIN | Apr 18 | May 3 | Apr 3 | Oct 22 | 188 |
| ILLINOIS CITY DAM 16 | Apr 18 | May 2 | Apr 5 | Oct 24 | 188 |
| PERRY 6 NW | Apr 18 | May 5 | Apr 4 | Oct 15 | 179 |
| WINCHESTER | Apr 18 | May 5 | Apr 3 | Oct 20 | 183 |
| ATHENS 4SW | Apr 19 | May 4 | Apr 6 | Oct 19 | 181 |
| AURORA | Apr 19 | May 4 | Apr 5 | Oct 23 | 185 |
| CHAMPAIGN WILLARD AP | Apr 19 | May 5 | Apr 6 | Oct 17 | 180 |
| CHICAGO PALWAUKEE AP | Apr 19 | May 3 | Apr 4 | Oct 26 | 190 |
| JACKSONVILLE 2E | Apr 19 | May 5 | Apr 5 | Oct 17 | 179 |
| JOLIET BRANDON RD DAM | Apr 19 | May 7 | Apr 3 | Oct 25 | 188 |
| KANKAKEE METRO WASTEWATER | Apr 19 | May 3 | Apr 5 | Oct 24 | 188 |
| LITTLE RED SCHOOL HSE | Apr 19 | May 5 | Apr 6 | Oct 22 | 183 |
| ROCK ISLAND L&D 15 | Apr 19 | May 4 | Apr 6 | Oct 22 | 184 |
| ROSICLARE 5NW | Apr 19 | May 8 | Apr 3 | Oct 20 | 181 |
| SIDELL 4N | Apr 19 | May 3 | Apr 4 | Oct 19 | 181 |
| GALESBURG | Apr 20 | May 5 | Apr 6 | Oct 19 | 180 |
| GENESEO | Apr 20 | May 6 | Apr 6 | Oct 20 | 180 |
| LACON | Apr 20 | May 7 | Apr 5 | Oct 17 | 178 |
| LINCOLN | Apr 20 | May 4 | Apr 5 | Oct 16 | 179 |
| MORRIS 1 NW | Apr 20 | May 6 | Apr 6 | Oct 23 | 184 |
| OGDEN | Apr 20 | May 7 | Apr 7 | Oct 21 | 182 |
| OTTAWA 5SW | Apr 20 | May 5 | Apr 6 | Oct 22 | 183 |
| ROMEOVILLE WFO | Apr 20 | May 6 | Apr 7 | Oct 22 | 184 |
| BLOOMINGTON 5W | Apr 21 | May 5 | Apr 7 | Oct 20 | 181 |
| CONGERVILLE 2NW | Apr 21 | May 7 | Apr 7 | Oct 17 | 178 |
| DANVILLE | Apr 21 | May 7 | Apr 6 | Oct 20 | 181 |
| DIXON 1W | Apr 21 | May 5 | Apr 7 | Oct 19 | 180 |
| GIBSON CITY | Apr 21 | May 5 | Apr 10 | Oct 17 | 178 |
| KNOXVILLE | Apr 21 | May 6 | Apr 7 | Oct 20 | 181 |
| LA HARPE | Apr 21 | May 5 | Apr 6 | Oct 19 | 180 |
| PARIS STP | Apr 21 | May 9 | Apr 6 | Oct 20 | 179 |
| RANTOUL | Apr 21 | May 6 | Apr 7 | Oct 18 | 179 |
| ALEDO | Apr 22 | May 6 | Apr 7 | Oct 19 | 181 |
| AVON | Apr 22 | May 8 | Apr 7 | Oct 19 | 177 |
| HOOPESTON | Apr 22 | May 8 | Apr 7 | Oct 19 | 180 |
| MONMOUTH | Apr 22 | May 10 | Apr 9 | Oct 15 | 174 |
| MONMOUTH 4NW | Apr 22 | May 7 | Apr 7 | Oct 14 | 174 |
| PRINCETON | Apr 22 | May 7 | Apr 9 | Oct 17 | 177 |
| PRINCEVILLE | Apr 22 | May 6 | Apr 8 | Oct 14 | 174 |
| ANTIOCH | Apr 23 | May 9 | Apr 9 | Oct 21 | 179 |
| CHAMPAIGN 9 SW | Apr 23 | May 9 | Apr 9 | Oct 13 | 170 |
| CHENOA | Apr 23 | May 7 | Apr 9 | Oct 15 | 174 |
| PARK FOREST | Apr 23 | May 11 | Apr 9 | Oct 20 | 179 |
| PAXTON 2 WSW | Apr 23 | May 9 | Apr 9 | Oct 12 | 170 |
| DE KALB | Apr 24 | May 10 | Apr 9 | Oct 18 | 177 |
| HENNEPIN WTR TRMT PLT | Apr 24 | May 10 | Apr 11 | Oct 17 | 174 |
| KEWANEE 1 E | Apr 24 | May 8 | Apr 10 | Oct 17 | 175 |
| LAKE VILLA 2NE | Apr 24 | May 9 | Apr 11 | Oct 23 | 180 |
| MOLINE QUAD CITY INTL AP | Apr 24 | May 9 | Apr 9 | Oct 18 | 176 |
| PERU | Apr 24 | May 8 | Apr 11 | Oct 18 | 176 |
| ROCKFORD GTR ROCKFORD AP | Apr 24 | May 8 | Apr 10 | Oct 17 | 174 |
| WALNUT | Apr 24 | May 9 | Apr 10 | Oct 14 | 172 |
| WATSEKA 2 NW | Apr 24 | May 10 | Apr 10 | Oct 16 | 174 |
| BARRINGTON 3SW | Apr 25 | May 12 | Apr 10 | Oct 19 | 177 |
| CRYSTAL LAKE 4NW | Apr 25 | May 9 | Apr 11 | Oct 22 | 179 |
| NORMAL 4NE | Apr 25 | May 11 | Apr 11 | Oct 16 | 172 |
| PIPER CITY | Apr 25 | May 10 | Apr 11 | Oct 20 | 175 |
| WEST CHICAGO DUPAGE AP | Apr 25 | May 12 | Apr 11 | Oct 19 | 174 |
| CHICAGO BOTANIC GARDEN | Apr 26 | May 11 | Apr 11 | Oct 21 | 176 |
| ELGIN | Apr 26 | May 12 | Apr 12 | Oct 18 | 174 |
| FREEPORT WASTE WTP | Apr 26 | May 11 | Apr 11 | Oct 13 | 169 |
| GALENA | Apr 26 | May 11 | Apr 11 | Oct 15 | 170 |
| GALVA | Apr 26 | May 11 | Apr 12 | Oct 12 | 166 |
| MINONK | Apr 26 | May 10 | Apr 11 | Oct 17 | 173 |
| MORRISON | Apr 26 | May 11 | Apr 13 | Oct 13 | 167 |
| ROCHELLE | Apr 26 | May 12 | Apr 11 | Oct 13 | 168 |
| COMPTON 1 NW | Apr 27 | May 14 | Apr 12 | Oct 12 | 167 |
| DWIGHT | Apr 27 | May 14 | Apr 14 | Oct 15 | 170 |
| MARSEILLES LOCK | Apr 27 | May 13 | Apr 12 | Oct 17 | 171 |
| PAW PAW 2S | Apr 27 | May 12 | Apr 12 | Oct 15 | 171 |
| STOCKTON 3 NNE | Apr 27 | May 12 | Apr 12 | Oct 9 | 165 |
| WHEATON 3 SE | Apr 27 | May 14 | Apr 12 | Oct 17 | 173 |
| ALTONA | Apr 28 | May 12 | Apr 15 | Oct 12 | 165 |
| CHICAGO AURORA MUNI AP | Apr 28 | May 11 | Apr 14 | Oct 13 | 166 |
| LISLE-MORTON ARBORETUM | Apr 28 | May 14 | Apr 14 | Oct 16 | 169 |
| MARENGO | Apr 28 | May 14 | Apr 15 | Oct 12 | 166 |
| SHABBONA 5 NNE | Apr 28 | May 13 | Apr 14 | Oct 10 | 163 |
| MUNDELEIN 4 WSW | Apr 29 | May 15 | Apr 14 | Oct 20 | 172 |
| POLO 5NW | Apr 29 | May 14 | Apr 15 | Oct 7 | 161 |
| CHICAGO WAUKEGAN RGNL AP | Apr 30 | May 16 | Apr 14 | Oct 21 | 173 |
| STREAMWOOD | Apr 30 | May 16 | Apr 17 | Oct 13 | 163 |
| WAUKEGAN | Apr 30 | May 14 | Apr 15 | Oct 19 | 170 |
| ELIZABETH | May 1 | May 17 | Apr 17 | Oct 9 | 160 |
| MC HENRY -WG STRATTON L&D | May 1 | May 19 | Apr 16 | Oct 11 | 162 |
| MT CARROLL | May 2 | May 18 | Apr 18 | Oct 7 | 154 |
How to read the three dates
Average is the date by which, in half of the years between 1991 and 2020, the last 32 °F night had already happened. Safe is later: only one year in ten saw a frost after it, which is the date to set out frost-tender plants such as dahlia tubers and zinnia seedlings. Early is the risky end, with a frost after it in nine years out of ten.
Every figure is for the weather station, not for your garden. A valley bottom, a north slope or a spot near a lake can run a week or two either way. Cities are warmer than the countryside around them.
Where the numbers come from
The dates are NOAA's U.S. Climate Normals for 1991 to 2020, computed by the National Centers for Environmental Information for every station with thirty years of daily minimum temperatures. ZIP codes are matched to the nearest such station within 150 km using U.S. Census Bureau ZIP Code Tabulation Area centroids. Stations that never see a frost, such as much of south Florida, report no date and are left out.