Michigan frost dates: O
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Oak Park | Apr 27 | Oct 25 | 181 d | 6b |
| Oakland | Apr 26 | Oct 22 | 179 d | 6a |
| Oakley | May 1 | Oct 15 | 167 d | 6a |
| Oden | May 16 | Oct 9 | 146 d | 5a |
| Okemos | Apr 28 | Oct 17 | 172 d | 6a |
| Old Mission | May 13 | Oct 19 | 159 d | 6b |
| Olivet | May 1 | Oct 15 | 167 d | 6a |
| Omena | May 9 | Oct 26 | 170 d | 6b |
| Omer | May 5 | Oct 10 | 158 d | 5b |
| Onaway | May 22 | Oct 2 | 133 d | 5a |
| Onekama | May 14 | Oct 12 | 151 d | 6b |
| Onondaga | Apr 30 | Oct 14 | 167 d | 6a |
| Onsted | May 5 | Oct 10 | 158 d | 6a |
| Ontonagon | May 27 | Oct 1 | 127 d | 5a |
| Orleans | May 3 | Oct 12 | 162 d | 6a |
| Ortonville | May 1 | Oct 14 | 166 d | 6a |
| Oscoda | May 8 | Oct 5 | 150 d | 5b |
| Oshtemo | Apr 28 | Oct 18 | 173 d | 6a |
| Osseo | May 3 | Oct 12 | 162 d | 6a |
| Ossineke | May 5 | Oct 17 | 165 d | 6a |
| Otisville | May 8 | Oct 5 | 150 d | 6a |
| Otsego | May 4 | Oct 15 | 164 d | 6a |
| Ottawa Lake | Apr 29 | Oct 13 | 167 d | 6a |
| Otter Lake | May 4 | Oct 13 | 162 d | 6a |
| Ovid | May 1 | Oct 15 | 167 d | 6a |
| Owendale | May 7 | Oct 10 | 156 d | 6a |
| Owosso | May 1 | Oct 15 | 167 d | 6a |
| Oxford | Apr 26 | Oct 22 | 179 d | 6a |