Illinois frost dates: M
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Macedonia | Apr 11 | Oct 21 | 193 d | 6b |
| Machesney Park | May 1 | Oct 12 | 164 d | 5b |
| Mackinaw | Apr 21 | Oct 17 | 179 d | 6a |
| Macomb | Apr 17 | Oct 22 | 188 d | 6a |
| Macon | Apr 14 | Oct 24 | 193 d | 6a |
| Madison | Apr 1 | Nov 4 | 217 d | 7a |
| Maeystown | Apr 9 | Oct 26 | 200 d | 7a |
| Magnolia | Apr 18 | Oct 22 | 187 d | 5b |
| Mahomet | Apr 23 | Oct 13 | 173 d | 6a |
| Makanda | Apr 9 | Oct 22 | 196 d | 7a |
| Malden | Apr 22 | Oct 17 | 178 d | 5b |
| Malta | Apr 24 | Oct 18 | 177 d | 5b |
| Manchester | Apr 13 | Oct 22 | 192 d | 6a |
| Manhattan | Apr 19 | Oct 25 | 189 d | 6a |
| Manito | Apr 17 | Oct 19 | 185 d | 6a |
| Manlius | Apr 24 | Oct 14 | 173 d | 5b |
| Mansfield | Apr 23 | Oct 13 | 173 d | 6a |
| Manteno | Apr 19 | Oct 24 | 188 d | 5b |
| Maple Park | Apr 24 | Oct 18 | 177 d | 5b |
| Mapleton | Apr 16 | Oct 23 | 190 d | 6a |
| Maquon | Apr 21 | Oct 20 | 182 d | 5b |
| Marengo | Apr 28 | Oct 12 | 167 d | 5b |
| Marietta | Apr 17 | Oct 22 | 188 d | 6a |
| Marine | Apr 12 | Oct 20 | 191 d | 6b |
| Marion | Apr 9 | Oct 22 | 196 d | 7a |
| Marissa | Apr 12 | Oct 22 | 193 d | 7a |
| Mark | Apr 24 | Oct 17 | 176 d | 5b |
| Markham | Apr 23 | Oct 20 | 180 d | 6a |
| Maroa | Apr 14 | Oct 24 | 193 d | 6a |
| Marseilles | Apr 27 | Oct 17 | 173 d | 5b |
| Marshall | Apr 21 | Oct 20 | 182 d | 6a |
| Martinsville | Apr 14 | Oct 20 | 189 d | 6b |
| Martinton | Apr 24 | Oct 16 | 175 d | 5b |
| Maryville | Apr 8 | Oct 26 | 201 d | 7a |
| Mascoutah | Apr 12 | Oct 20 | 191 d | 6b |
| Mason | Apr 13 | Oct 24 | 194 d | 6b |
| Mason City | Apr 17 | Oct 18 | 184 d | 6a |
| Matherville | Apr 22 | Oct 19 | 180 d | 5b |
| Matteson | Apr 23 | Oct 20 | 180 d | 6a |
| Mattoon | Apr 11 | Oct 29 | 201 d | 6a |
| Maunie | Apr 15 | Oct 19 | 187 d | 7a |
| Maywood | Apr 11 | Oct 31 | 203 d | 6a |
| Mazon | Apr 27 | Oct 15 | 171 d | 5b |
| Mc Clure | Apr 5 | Oct 25 | 203 d | 7a |
| Mc Connell | Apr 27 | Oct 9 | 165 d | 5a |
| Mc Lean | Apr 21 | Oct 20 | 182 d | 6a |
| Mc Leansboro | Apr 11 | Oct 21 | 193 d | 6b |
| Mc Nabb | Apr 18 | Oct 22 | 187 d | 5b |
| Mchenry | May 1 | Oct 11 | 163 d | 5b |
| Mechanicsburg | Apr 15 | Oct 22 | 190 d | 6a |
| Media | Apr 8 | Oct 29 | 204 d | 5b |
| Medinah | Apr 16 | Oct 28 | 195 d | 5b |
| Medora | Apr 14 | Oct 19 | 188 d | 6b |
| Melrose Park | Apr 16 | Oct 28 | 195 d | 6a |
| Melvin | Apr 21 | Oct 17 | 179 d | 6a |
| Menard | Apr 8 | Oct 30 | 205 d | 7a |
| Mendon | Apr 14 | Oct 23 | 192 d | 6a |
| Mendota | Apr 27 | Oct 15 | 171 d | 5b |
| Meredosia | Apr 18 | Oct 20 | 185 d | 6a |
| Merna | Apr 25 | Oct 16 | 174 d | 6a |
| Metamora | Apr 21 | Oct 17 | 179 d | 6a |
| Metcalf | Apr 19 | Oct 19 | 183 d | 6a |
| Metropolis | Apr 6 | Oct 27 | 204 d | 7a |
| Michael | Apr 20 | Oct 20 | 183 d | 6a |
| Middletown | Apr 17 | Oct 18 | 184 d | 6a |
| Midlothian | Apr 10 | Nov 1 | 205 d | 6a |
| Milan | Apr 24 | Oct 18 | 177 d | 5b |
| Milford | Apr 22 | Oct 19 | 180 d | 6a |
| Mill Shoals | Apr 7 | Oct 26 | 202 d | 6b |
| Millbrook | Apr 28 | Oct 13 | 168 d | 5b |
| Millcreek | Apr 8 | Oct 29 | 204 d | 7a |
| Milledgeville | Apr 29 | Oct 7 | 161 d | 5a |
| Miller City | Apr 2 | Oct 31 | 212 d | 7a |
| Millington | Apr 28 | Oct 13 | 168 d | 5b |
| Millstadt | Apr 8 | Oct 26 | 201 d | 7a |
| Milmine | Apr 16 | Oct 22 | 189 d | 6a |
| Milton | Apr 14 | Oct 21 | 190 d | 6a |
| Mineral | Apr 24 | Oct 17 | 176 d | 5b |
| Minier | Apr 21 | Oct 20 | 182 d | 6a |
| Minonk | Apr 26 | Oct 17 | 174 d | 5b |
| Minooka | Apr 16 | Oct 26 | 193 d | 5b |
| Mode | Apr 10 | Oct 24 | 197 d | 6b |
| Modesto | Apr 7 | Oct 29 | 205 d | 6b |
| Modoc | Apr 8 | Oct 30 | 205 d | 7a |
| Mokena | Apr 20 | Oct 22 | 185 d | 6a |
| Moline | Apr 24 | Oct 18 | 177 d | 5b |
| Momence | Apr 19 | Oct 24 | 188 d | 5b |
| Monee | Apr 23 | Oct 20 | 180 d | 6a |
| Monmouth | Apr 22 | Oct 15 | 176 d | 5b |
| Monroe Center | Apr 24 | Oct 17 | 176 d | 5b |
| Montgomery | Apr 19 | Oct 23 | 187 d | 5b |
| Monticello | Apr 23 | Oct 13 | 173 d | 6a |
| Montrose | Apr 13 | Oct 22 | 192 d | 6b |
| Mooseheart | Apr 19 | Oct 23 | 187 d | 5b |
| Moro | Apr 4 | Nov 5 | 215 d | 6b |
| Morris | Apr 20 | Oct 23 | 186 d | 5b |
| Morrison | Apr 26 | Oct 13 | 170 d | 5b |
| Morrisonville | Apr 12 | Oct 20 | 191 d | 6a |
| Morton | Apr 21 | Oct 17 | 179 d | 6a |
| Morton Grove | Apr 26 | Oct 21 | 178 d | 6a |
| Mossville | Apr 16 | Oct 23 | 190 d | 6a |
| Mound City | Apr 2 | Oct 31 | 212 d | 7a |
| Mounds | Apr 2 | Oct 31 | 212 d | 7a |
| Mount Auburn | Apr 14 | Oct 24 | 193 d | 6a |
| Mount Carmel | Apr 2 | Oct 31 | 212 d | 6b |
| Mount Carroll | May 2 | Oct 7 | 158 d | 5a |
| Mount Erie | Apr 7 | Oct 26 | 202 d | 6b |
| Mount Morris | Apr 29 | Oct 7 | 161 d | 5b |
| Mount Olive | Apr 13 | Oct 24 | 194 d | 6b |
| Mount Prospect | Apr 19 | Oct 26 | 190 d | 6a |
| Mount Pulaski | Apr 20 | Oct 16 | 179 d | 6a |
| Mount Sterling | Apr 18 | Oct 15 | 180 d | 6a |
| Mount Vernon | Apr 11 | Oct 22 | 194 d | 6b |
| Moweaqua | Apr 14 | Oct 24 | 193 d | 6a |
| Mozier | Apr 20 | Oct 20 | 183 d | 6b |
| Mt Zion | Apr 16 | Oct 22 | 189 d | 6a |
| Muddy | Apr 7 | Oct 26 | 202 d | 7a |
| Mulberry Grove | Apr 10 | Oct 24 | 197 d | 6b |
| Mulkeytown | Apr 6 | Oct 22 | 199 d | 7a |
| Muncie | Apr 20 | Oct 21 | 184 d | 6a |
| Mundelein | Apr 29 | Oct 20 | 174 d | 5b |
| Murdock | Apr 15 | Oct 20 | 188 d | 6a |
| Murphysboro | Apr 9 | Oct 22 | 196 d | 7a |
| Murrayville | Apr 17 | Oct 21 | 187 d | 6a |