Illinois frost dates: A
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Abingdon | Apr 21 | Oct 20 | 182 d | 5b |
| Adair | Apr 17 | Oct 22 | 188 d | 6a |
| Addieville | Apr 7 | Oct 26 | 202 d | 6b |
| Addison | Apr 16 | Oct 28 | 195 d | 6a |
| Albany | Apr 22 | Oct 16 | 177 d | 5b |
| Albers | Apr 12 | Oct 20 | 191 d | 6b |
| Albion | Apr 4 | Oct 28 | 207 d | 6b |
| Alden | Apr 25 | Oct 22 | 180 d | 5b |
| Aledo | Apr 22 | Oct 19 | 180 d | 5b |
| Alexander | Apr 19 | Oct 17 | 181 d | 6a |
| Alexis | Apr 22 | Oct 15 | 176 d | 5b |
| Algonquin | Apr 26 | Oct 18 | 175 d | 5b |
| Alhambra | Apr 4 | Nov 5 | 215 d | 6b |
| Allendale | Apr 2 | Oct 31 | 212 d | 6b |
| Allerton | Apr 19 | Oct 19 | 183 d | 6a |
| Alma | Apr 9 | Oct 26 | 200 d | 6b |
| Alpha | Apr 28 | Oct 12 | 167 d | 5b |
| Alsey | Apr 18 | Oct 20 | 185 d | 6a |
| Alsip | Apr 10 | Nov 1 | 205 d | 6a |
| Altamont | Apr 13 | Oct 24 | 194 d | 6b |
| Alto Pass | Apr 8 | Oct 29 | 204 d | 7a |
| Alton | Apr 4 | Nov 5 | 215 d | 7a |
| Altona | Apr 28 | Oct 12 | 167 d | 5b |
| Alvin | Apr 21 | Oct 20 | 182 d | 6a |
| Amboy | Apr 21 | Oct 19 | 181 d | 5b |
| Anchor | Apr 21 | Oct 17 | 179 d | 6a |
| Ancona | Apr 12 | Oct 28 | 199 d | 5b |
| Andalusia | Apr 19 | Oct 22 | 186 d | 5b |
| Andover | Apr 20 | Oct 20 | 183 d | 5b |
| Anna | Apr 8 | Oct 29 | 204 d | 7a |
| Annapolis | Apr 13 | Oct 22 | 192 d | 6b |
| Annawan | Apr 24 | Oct 17 | 176 d | 5b |
| Antioch | Apr 23 | Oct 21 | 181 d | 5b |
| Apple River | Apr 27 | Oct 9 | 165 d | 5a |
| Arcola | Apr 15 | Oct 20 | 188 d | 6a |
| Arenzville | Apr 19 | Oct 17 | 181 d | 6a |
| Argenta | Apr 16 | Oct 22 | 189 d | 6a |
| Arlington | Apr 24 | Oct 18 | 177 d | 5b |
| Arlington Heights | Apr 19 | Oct 26 | 190 d | 6a |
| Armington | Apr 20 | Oct 16 | 179 d | 6a |
| Armstrong | Apr 20 | Oct 21 | 184 d | 6a |
| Aroma Park | Apr 19 | Oct 24 | 188 d | 5b |
| Arrowsmith | Apr 21 | Oct 17 | 179 d | 6a |
| Arthur | Apr 15 | Oct 20 | 188 d | 6a |
| Ashkum | Apr 24 | Oct 16 | 175 d | 5b |
| Ashland | Apr 13 | Oct 21 | 191 d | 6a |
| Ashley | Apr 7 | Oct 26 | 202 d | 6b |
| Ashmore | Apr 15 | Oct 23 | 191 d | 6a |
| Ashton | Apr 26 | Oct 13 | 170 d | 5b |
| Assumption | Apr 17 | Oct 23 | 189 d | 6a |
| Astoria | Apr 16 | Oct 23 | 190 d | 6a |
| Athens | Apr 19 | Oct 19 | 183 d | 6a |
| Atkinson | Apr 20 | Oct 20 | 183 d | 5b |
| Atlanta | Apr 20 | Oct 16 | 179 d | 6a |
| Atwood | Apr 15 | Oct 20 | 188 d | 6a |
| Auburn | Apr 7 | Oct 29 | 205 d | 6a |
| Augusta | Apr 18 | Oct 21 | 186 d | 6a |
| Aurora | Apr 19 | Oct 23 | 187 d | 5b |
| Ava | Apr 9 | Oct 22 | 196 d | 7a |
| Aviston | Apr 6 | Oct 29 | 206 d | 6b |
| Avon | Apr 22 | Oct 19 | 180 d | 5b |