Illinois frost dates
Across 170 weather stations in Illinois, the median last spring frost runs from Apr 2 in Cairo to May 2 in Mount Carroll, and the first fall frost from Oct 7 to Nov 5.
Illinois at a glance
- Weather stations
- 170
- Earliest last frost
- Apr 2 Cairo
- Latest last frost
- May 2 Mount Carroll
- Longest season
- 216 days Grand Chain Dam
- Typical season
- about 185 frost-free days
- Hardiness zones
- Zones 5a to 7a
Frost dates by weather station
| Weather station | Last spring frost | First fall frost | Frost-free days | Zone |
|---|---|---|---|---|
| Albion | Apr 4 | Oct 28 | 206 | 6b |
| Aledo | Apr 22 | Oct 19 | 181 | 5b |
| Alton - Melvin Price Lock and Dam | Apr 4 | Nov 5 | 214 | 7a |
| Altona | Apr 28 | Oct 12 | 165 | 5b |
| Anna | Apr 8 | Oct 29 | 203 | 7a |
| Antioch | Apr 23 | Oct 21 | 179 | 5b |
| Athens | Apr 19 | Oct 19 | 181 | 6a |
| Aurora | Apr 19 | Oct 23 | 185 | 5b |
| Avon | Apr 22 | Oct 19 | 177 | 5b |
| Barrington | Apr 25 | Oct 19 | 177 | 5b |
| Belleville Siu Research | Apr 12 | Oct 20 | 189 | 6b |
| Bentley | Apr 13 | Oct 22 | 191 | 6a |
| Benton | Apr 4 | Oct 28 | 206 | 7a |
| Bloomington | Apr 21 | Oct 20 | 181 | 6a |
| Brookport Dam | Apr 6 | Oct 27 | 203 | 7a |
| Brownstown | Apr 3 | Oct 24 | 202 | 6b |
| Cahokia | Apr 6 | Oct 27 | 203 | 7a |
| Cahokia St. Louis Airport | Apr 8 | Oct 26 | 200 | 7a |
| Cairo | Apr 2 | Oct 31 | 211 | 7a |
| Carbondale Sewage Plant | Apr 9 | Oct 22 | 195 | 7a |
| Carbondale Southern Il Airport | Apr 9 | Oct 22 | 195 | 7a |
| Carlinville | Apr 14 | Oct 21 | 188 | 6b |
| Carlyle Reservoir | Apr 6 | Oct 29 | 204 | 6b |
| Carmi | Apr 15 | Oct 19 | 183 | 7a |
| Casey | Apr 14 | Oct 20 | 187 | 6b |
| Champaign 3 mi S | Apr 15 | Oct 24 | 190 | 6a |
| Champaign 9 mi SW | Apr 23 | Oct 13 | 170 | 6a |
| Champaign Willard Airport | Apr 19 | Oct 17 | 180 | 6a |
| Channahon Dresden Island Dam | Apr 16 | Oct 26 | 191 | 5b |
| Charleston | Apr 15 | Oct 23 | 187 | 6a |
| Chenoa | Apr 23 | Oct 15 | 174 | 5b |
| Chicago Aurora Municipal Airport | Apr 28 | Oct 13 | 166 | 5b |
| Chicago Botanic Garden | Apr 26 | Oct 21 | 176 | 6a |
| Chicago Midway Airport | Apr 11 | Oct 31 | 201 | 6a |
| Chicago Midway Airport 3 mi SW | Apr 10 | Nov 1 | 203 | 6a |
| Chicago Northerly Island | Apr 10 | Nov 5 | 208 | 6b |
| Chicago O'Hare International Airport | Apr 16 | Oct 28 | 193 | 6a |
| Chicago Palwaukee Airport | Apr 19 | Oct 26 | 190 | 6a |
| Chicago Waukegan Regional Airport | Apr 30 | Oct 21 | 173 | 6a |
| Compton | Apr 27 | Oct 12 | 167 | 5b |
| Congerville | Apr 21 | Oct 17 | 178 | 5b |
| Crystal Lake | Apr 25 | Oct 22 | 179 | 5b |
| Danville | Apr 21 | Oct 20 | 181 | 6a |
| De Kalb | Apr 24 | Oct 18 | 177 | 5b |
| Decatur Airport | Apr 16 | Oct 22 | 187 | 6a |
| Decatur Water Plant | Apr 14 | Oct 24 | 192 | 6a |
| Dixon | Apr 21 | Oct 19 | 180 | 5b |
| Dixon Springs Agric Center | Apr 14 | Oct 21 | 189 | 7a |
| Du Quoin | Apr 6 | Oct 22 | 199 | 7a |
| Dwight | Apr 27 | Oct 15 | 170 | 5b |
| Effingham | Apr 13 | Oct 24 | 191 | 6b |
| Elgin | Apr 26 | Oct 18 | 174 | 5b |
| Elizabeth | May 1 | Oct 9 | 160 | 5a |
| Fairfield Radio Wfiw | Apr 7 | Oct 26 | 201 | 6b |
| Flora | Apr 9 | Oct 24 | 198 | 6b |
| Flora 5 mi NW | Apr 10 | Oct 23 | 196 | 6b |
| Freeport Waste Water Plant | Apr 26 | Oct 13 | 169 | 5a |
| Fulton Lock and Dam | Apr 13 | Oct 26 | 195 | 5b |
| Galena | Apr 26 | Oct 15 | 170 | 5a |
| Galesburg | Apr 20 | Oct 19 | 180 | 5b |
| Galva | Apr 26 | Oct 12 | 166 | 5b |
| Geneseo | Apr 20 | Oct 20 | 180 | 5b |
| Gibson City | Apr 21 | Oct 17 | 178 | 6a |
| Gladstone Dam | Apr 8 | Oct 29 | 202 | 6a |
| Golden | Apr 18 | Oct 21 | 187 | 6a |
| Grand Chain Dam | Apr 3 | Nov 5 | 216 | 7a |
| Grayville | Apr 7 | Oct 25 | 201 | 7a |
| Harrisburg | Apr 7 | Oct 26 | 202 | 7a |
| Havana | Apr 17 | Oct 19 | 185 | 6a |
| Hennepin | Apr 18 | Oct 22 | 188 | 5b |
| Hennepin Water Trmt Plant | Apr 24 | Oct 17 | 174 | 5b |
| Hillsboro | Apr 13 | Oct 24 | 192 | 6b |
| Hoopeston | Apr 22 | Oct 19 | 180 | 6a |
| Illinois City Dam | Apr 18 | Oct 24 | 188 | 5b |
| Iuka | Apr 9 | Oct 24 | 196 | 6b |
| Jacksonville | Apr 17 | Oct 21 | 186 | 6a |
| Jacksonville 2 mi E | Apr 19 | Oct 17 | 179 | 6a |
| Jerseyville | Apr 14 | Oct 19 | 187 | 6b |
| Joliet Brandon Road Dam | Apr 19 | Oct 25 | 188 | 6a |
| Kankakee Metro Wastewater | Apr 19 | Oct 24 | 188 | 5b |
| Kaskaskia River Navigation Lock | Apr 8 | Oct 30 | 202 | 7a |
| Kewanee | Apr 24 | Oct 17 | 175 | 5b |
| Knoxville | Apr 21 | Oct 20 | 181 | 5b |
| La Harpe | Apr 21 | Oct 19 | 180 | 6a |
| Lacon | Apr 20 | Oct 17 | 178 | 5b |
| Lake Villa | Apr 24 | Oct 23 | 180 | 5b |
| Lawrenceville | Apr 12 | Oct 25 | 193 | 6b |
| Lawrenceville International Airport | Apr 8 | Oct 26 | 200 | 6b |
| Lincoln | Apr 20 | Oct 16 | 179 | 6a |
| Lisle-Morton Arboretum | Apr 28 | Oct 16 | 169 | 5b |
| Little Red School Hse | Apr 19 | Oct 22 | 183 | 6a |
| Marengo | Apr 28 | Oct 12 | 166 | 5b |
| Marseilles Lock | Apr 27 | Oct 17 | 171 | 5b |
| Mason City | Apr 17 | Oct 18 | 182 | 6a |
| Mattoon | Apr 11 | Oct 29 | 199 | 6a |
| Mattoon Coles County Airport | Apr 15 | Oct 24 | 189 | 6a |
| McHenry -Wg Stratton Lock and Dam | May 1 | Oct 11 | 162 | 5b |
| McLeansboro | Apr 11 | Oct 21 | 190 | 6b |
| Minonk | Apr 26 | Oct 17 | 173 | 5b |
| Moline Quad City International Airport | Apr 24 | Oct 18 | 176 | 5b |
| Monmouth | Apr 22 | Oct 15 | 174 | 5b |
| Monmouth 4 mi NW | Apr 22 | Oct 14 | 174 | 5b |
| Morris | Apr 20 | Oct 23 | 184 | 5b |
| Morrison | Apr 26 | Oct 13 | 167 | 5b |
| Morrisonville | Apr 12 | Oct 20 | 190 | 6a |
| Mount Carmel | Apr 2 | Oct 31 | 209 | 6b |
| Mount Carroll | May 2 | Oct 7 | 154 | 5a |
| Mount Vernon | Apr 11 | Oct 22 | 193 | 6b |
| Mundelein | Apr 29 | Oct 20 | 172 | 5b |
| Nashville | Apr 7 | Oct 26 | 201 | 6b |
| Neoga | Apr 16 | Oct 20 | 185 | 6b |
| New Boston Dam | Apr 14 | Oct 24 | 190 | 5b |
| Newton | Apr 13 | Oct 22 | 190 | 6b |
| Newton 6 mi SSE | Apr 13 | Oct 22 | 191 | 6b |
| Normal | Apr 25 | Oct 16 | 172 | 6a |
| Ogden | Apr 20 | Oct 21 | 182 | 6a |
| Olney | Apr 15 | Oct 23 | 189 | 6b |
| Ottawa | Apr 20 | Oct 22 | 183 | 5b |
| Palestine | Apr 12 | Oct 22 | 193 | 6b |
| Pana | Apr 17 | Oct 23 | 188 | 6b |
| Paris Treatment Plant | Apr 21 | Oct 20 | 179 | 6a |
| Park Forest | Apr 23 | Oct 20 | 179 | 6a |
| Paw Paw | Apr 27 | Oct 15 | 171 | 5b |
| Paxton | Apr 23 | Oct 12 | 170 | 6a |
| Peoria Greater Peoria Airport | Apr 16 | Oct 23 | 189 | 6a |
| Perry | Apr 18 | Oct 15 | 179 | 6a |
| Peru | Apr 24 | Oct 18 | 176 | 5b |
| Petersburg | Apr 13 | Oct 21 | 189 | 6a |
| Piper City | Apr 25 | Oct 20 | 175 | 6a |
| Pittsfield | Apr 14 | Oct 21 | 189 | 6a |
| Polo | Apr 29 | Oct 7 | 161 | 5b |
| Pontiac | Apr 16 | Oct 24 | 191 | 6a |
| Prairie City | Apr 17 | Oct 22 | 185 | 6a |
| Princeton | Apr 22 | Oct 17 | 177 | 5b |
| Princeville | Apr 22 | Oct 14 | 174 | 5b |
| Quincy Dam | Apr 8 | Oct 30 | 204 | 6a |
| Quincy Regional Airport | Apr 14 | Oct 23 | 191 | 6a |
| Ramsey | Apr 15 | Oct 19 | 185 | 6b |
| Rantoul | Apr 21 | Oct 18 | 179 | 6a |
| Rend Lake Dam | Apr 4 | Oct 27 | 204 | 7a |
| Robinson | Apr 13 | Oct 22 | 190 | 6b |
| Rochelle | Apr 26 | Oct 13 | 168 | 5b |
| Rock Island Lock and Dam | Apr 19 | Oct 22 | 184 | 5b |
| Rockford Greater Rockford Airport | Apr 24 | Oct 17 | 174 | 5b |
| Romeoville | Apr 20 | Oct 22 | 184 | 6a |
| Rosiclare | Apr 19 | Oct 20 | 181 | 7a |
| Rushville | Apr 16 | Oct 23 | 189 | 6a |
| Salem | Apr 9 | Oct 26 | 197 | 6b |
| Shabbona | Apr 28 | Oct 10 | 163 | 5b |
| Shelbyville Dam | Apr 10 | Oct 24 | 195 | 6a |
| Sidell | Apr 19 | Oct 19 | 181 | 6a |
| Smithland Lock and Dam | Apr 3 | Oct 30 | 207 | 7a |
| Sparta | Apr 12 | Oct 22 | 191 | 7a |
| Springfield | Apr 15 | Oct 22 | 188 | 6a |
| Springfield Capital Airport | Apr 14 | Oct 20 | 187 | 6a |
| Stockton | Apr 27 | Oct 9 | 165 | 5a |
| Streamwood | Apr 30 | Oct 13 | 163 | 5b |
| Streator | Apr 12 | Oct 28 | 199 | 5b |
| Sullivan | Apr 15 | Oct 22 | 187 | 6a |
| Tuscola | Apr 15 | Oct 20 | 188 | 6a |
| Vandalia | Apr 10 | Oct 24 | 196 | 6b |
| Virden | Apr 7 | Oct 29 | 205 | 6b |
| Walnut | Apr 24 | Oct 14 | 172 | 5b |
| Watseka | Apr 24 | Oct 16 | 174 | 5b |
| Waukegan | Apr 30 | Oct 19 | 170 | 6a |
| West Chicago Dupage Airport | Apr 25 | Oct 19 | 174 | 5b |
| Wheaton | Apr 27 | Oct 17 | 173 | 5b |
| White Hall | Apr 13 | Oct 22 | 190 | 6a |
| Winchester | Apr 18 | Oct 20 | 183 | 6a |
| Windsor | Apr 16 | Oct 22 | 187 | 6a |
Median dates from NOAA 1991–2020 climate normals. How to read them.