Utah frost dates: M
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Magna | Apr 3 | Nov 4 | 215 d | 7b |
| Manila | May 22 | Sep 29 | 130 d | 5b |
| Manti | May 11 | Oct 6 | 148 d | 6a |
| Mantua | May 5 | Oct 5 | 153 d | 6a |
| Mapleton | Apr 25 | Oct 18 | 176 d | 7a |
| Marysvale | May 24 | Sep 25 | 124 d | 6a |
| Mayfield | May 11 | Oct 6 | 148 d | 6a |
| Meadow | Apr 30 | Oct 19 | 172 d | 6b |
| Mendon | May 12 | Sep 28 | 139 d | 6a |
| Mexican Hat | Apr 11 | Oct 30 | 202 d | 7b |
| Midvale | Apr 29 | Oct 22 | 176 d | 7b |
| Midway | May 31 | Sep 11 | 103 d | 6a |
| Milford | May 10 | Oct 2 | 145 d | 6a |
| Millville | May 12 | Sep 28 | 139 d | 6a |
| Minersville | May 10 | Oct 2 | 145 d | 6a |
| Moab | Apr 11 | Oct 23 | 195 d | 7a |
| Modena | May 20 | Oct 3 | 136 d | 7a |
| Mona | May 6 | Oct 10 | 157 d | 6b |
| Monroe | May 21 | Sep 24 | 126 d | 6a |
| Montezuma Creek | May 2 | Oct 10 | 161 d | 7a |
| Monticello | May 19 | Oct 2 | 136 d | 6b |
| Monument Valley | Apr 10 | Nov 1 | 205 d | 8a |
| Morgan | May 25 | Sep 24 | 122 d | 6a |
| Moroni | May 26 | Sep 25 | 122 d | 5b |
| Mount Carmel | May 15 | Oct 8 | 146 d | 7a |
| Mount Pleasant | May 26 | Sep 25 | 122 d | 5b |
| Mountain Home | May 31 | Sep 23 | 115 d | 6a |
| Myton | May 7 | Oct 5 | 151 d | 5b |