Colorado frost dates: M
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Mack | Apr 27 | Oct 11 | 167 d | 7a |
| Manassa | May 28 | Sep 21 | 116 d | 5a |
| Mancos | Jun 4 | Sep 24 | 112 d | 6a |
| Manitou Springs | Jun 3 | Sep 17 | 106 d | 5b |
| Manzanola | May 2 | Oct 8 | 159 d | 6a |
| Marvel | Jun 1 | Sep 27 | 118 d | 6a |
| Masonville | May 12 | Oct 1 | 142 d | 5b |
| Matheson | May 12 | Oct 2 | 143 d | 5b |
| Maybell | Jun 16 | Sep 9 | 85 d | 6a |
| Mc Clave | Apr 24 | Oct 15 | 174 d | 6a |
| Mc Coy | Jun 14 | Sep 11 | 89 d | 5b |
| Mead | May 7 | Oct 5 | 151 d | 5b |
| Meeker | Jun 4 | Sep 16 | 104 d | 5b |
| Meredith | frost any month | 5a | ||
| Merino | Apr 30 | Oct 9 | 162 d | 5b |
| Mesa | May 17 | Sep 30 | 136 d | 6b |
| Mesa Verde National Park | May 6 | Oct 14 | 161 d | 7a |
| Milliken | May 2 | Oct 8 | 159 d | 5b |
| Minturn | Jun 21 | Sep 7 | 78 d | 5a |
| Model | May 4 | Oct 9 | 158 d | 6a |
| Moffat | May 26 | Sep 26 | 123 d | 5b |
| Molina | May 17 | Sep 30 | 136 d | 5b |
| Monarch | frost any month | 5b | ||
| Monte Vista | Jun 11 | Sep 13 | 94 d | 5a |
| Montrose | Apr 28 | Oct 14 | 169 d | 6b |
| Monument | May 14 | Oct 1 | 140 d | 5b |
| Morrison | May 2 | Oct 11 | 162 d | 5b |
| Mosca | May 30 | Sep 17 | 110 d | 5a |