Connecticut frost dates: M
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Madison | Apr 17 | Oct 27 | 193 d | 7a |
| Manchester | Apr 17 | Oct 26 | 192 d | 6b |
| Mansfield Center | Apr 28 | Oct 13 | 168 d | 6b |
| Mansfield Depot | Apr 19 | Oct 22 | 186 d | 6b |
| Marion | Apr 26 | Oct 16 | 173 d | 6b |
| Marlborough | Apr 17 | Oct 26 | 192 d | 6b |
| Mashantucket | Apr 14 | Oct 24 | 193 d | 6b |
| Meriden | Apr 26 | Oct 16 | 173 d | 6b |
| Middle Haddam | Apr 17 | Oct 26 | 192 d | 6b |
| Middlebury | Apr 25 | Oct 17 | 175 d | 6b |
| Middlefield | Apr 26 | Oct 16 | 173 d | 6b |
| Middletown | Apr 26 | Oct 16 | 173 d | 6b |
| Milford | Apr 5 | Nov 6 | 215 d | 7a |
| Milldale | Apr 26 | Oct 16 | 173 d | 6b |
| Monroe | Apr 25 | Oct 17 | 175 d | 6b |
| Montville | Apr 14 | Oct 24 | 193 d | 6b |
| Moodus | Apr 17 | Oct 26 | 192 d | 6b |
| Moosup | Apr 30 | Oct 15 | 168 d | 6b |
| Morris | May 8 | Oct 5 | 150 d | 6a |
| Mystic | Apr 8 | Nov 2 | 208 d | 7a |