Pennsylvania frost dates: M
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Mackeyville | Apr 30 | Oct 20 | 173 d | 6b |
| Macungie | Apr 26 | Oct 14 | 171 d | 7a |
| Madera | May 13 | Oct 1 | 141 d | 6a |
| Madison | May 1 | Oct 13 | 165 d | 6b |
| Madisonburg | May 5 | Oct 6 | 154 d | 6b |
| Mahaffey | May 4 | Oct 13 | 162 d | 6a |
| Mahanoy City | Apr 30 | Oct 22 | 175 d | 6b |
| Mahanoy Plane | Apr 30 | Oct 22 | 175 d | 6b |
| Mainesburg | May 6 | Oct 10 | 157 d | 6a |
| Mainland | Apr 24 | Oct 15 | 174 d | 7a |
| Malvern | Apr 18 | Oct 27 | 192 d | 7a |
| Mammoth | Apr 22 | Oct 25 | 186 d | 6b |
| Manchester | Apr 9 | Nov 2 | 207 d | 7a |
| Manheim | Apr 30 | Oct 10 | 163 d | 7a |
| Manns Choice | May 4 | Oct 10 | 159 d | 6b |
| Manor | Apr 22 | Oct 25 | 186 d | 6b |
| Manorville | May 4 | Oct 16 | 165 d | 6b |
| Mansfield | May 6 | Oct 10 | 157 d | 6a |
| Mapleton Depot | Apr 19 | Oct 28 | 192 d | 6b |
| Mar Lin | Apr 30 | Oct 22 | 175 d | 6b |
| Marble | May 9 | Oct 11 | 155 d | 6a |
| Marchand | May 10 | Oct 12 | 155 d | 6a |
| Marcus Hook | Mar 30 | Nov 16 | 231 d | 7b |
| Marianna | May 3 | Oct 15 | 165 d | 6b |
| Marienville | May 13 | Oct 7 | 147 d | 6a |
| Marietta | Apr 30 | Oct 10 | 163 d | 7a |
| Marion | Apr 18 | Oct 25 | 190 d | 7a |
| Marion Center | May 8 | Oct 13 | 158 d | 6a |
| Marion Heights | Apr 27 | Oct 20 | 176 d | 6b |
| Markleton | Apr 30 | Oct 18 | 171 d | 6a |
| Markleysburg | Apr 30 | Oct 18 | 171 d | 6a |
| Mars | May 7 | Oct 14 | 160 d | 6b |
| Marshalls Creek | May 1 | Oct 12 | 164 d | 6b |
| Marsteller | May 10 | Oct 5 | 148 d | 6a |
| Martin | Apr 28 | Oct 21 | 176 d | 6b |
| Martindale | Apr 14 | Nov 1 | 201 d | 7a |
| Martins Creek | Apr 30 | Oct 18 | 171 d | 7a |
| Martinsburg | Apr 23 | Oct 21 | 181 d | 6b |
| Mary D | Apr 30 | Oct 22 | 175 d | 6b |
| Marysville | Apr 15 | Oct 23 | 191 d | 7a |
| Masontown | Apr 28 | Oct 21 | 176 d | 6b |
| Matamoras | May 2 | Oct 12 | 163 d | 6b |
| Mather | May 3 | Oct 15 | 165 d | 6b |
| Mattawana | Apr 21 | Oct 24 | 186 d | 7a |
| Maxatawny | Apr 26 | Oct 14 | 171 d | 6b |
| Mayport | May 10 | Oct 12 | 155 d | 6a |
| Maytown | Apr 30 | Oct 10 | 163 d | 7a |
| Mc Alisterville | Apr 21 | Oct 24 | 186 d | 6b |
| Mc Clellandtown | Apr 28 | Oct 21 | 176 d | 6b |
| Mc Clure | Apr 21 | Oct 24 | 186 d | 6b |
| Mc Connellsburg | Apr 18 | Oct 25 | 190 d | 7a |
| Mc Connellstown | Apr 19 | Oct 28 | 192 d | 6b |
| Mc Donald | Apr 23 | Oct 23 | 183 d | 6b |
| Mc Elhattan | Apr 30 | Oct 20 | 173 d | 6b |
| Mc Ewensville | Apr 26 | Oct 20 | 177 d | 6b |
| Mc Grann | May 4 | Oct 16 | 165 d | 6b |
| Mc Intyre | May 8 | Oct 13 | 158 d | 6b |
| Mc Kean | Apr 26 | Nov 4 | 192 d | 6a |
| Mc Kees Rocks | Apr 24 | Oct 27 | 186 d | 6b |
| Mc Knightstown | Apr 28 | Oct 17 | 172 d | 7a |
| Mc Sherrystown | Apr 24 | Oct 20 | 179 d | 6b |
| Mc Veytown | Apr 21 | Oct 24 | 186 d | 7a |
| Mcadoo | Apr 30 | Oct 22 | 175 d | 6b |
| Mckeesport | May 2 | Oct 20 | 171 d | 6b |
| Meadow Lands | Apr 24 | Oct 23 | 182 d | 6b |
| Meadville | Apr 30 | Oct 23 | 176 d | 6a |
| Mechanicsburg | Apr 9 | Nov 1 | 206 d | 7a |
| Mechanicsville | Apr 13 | Oct 30 | 200 d | 7a |
| Media | Mar 30 | Nov 16 | 231 d | 7b |
| Mehoopany | May 14 | Oct 2 | 141 d | 6a |
| Melcroft | Apr 30 | Oct 17 | 170 d | 6a |
| Mendenhall | Apr 7 | Nov 4 | 211 d | 7a |
| Mentcle | May 8 | Oct 13 | 158 d | 6a |
| Mercer | May 15 | Oct 3 | 141 d | 6a |
| Mercersburg | Apr 7 | Nov 4 | 211 d | 7a |
| Merion Station | Mar 30 | Nov 17 | 232 d | 7b |
| Merrittstown | Apr 30 | Oct 18 | 171 d | 6b |
| Mertztown | Apr 26 | Oct 14 | 171 d | 6b |
| Meshoppen | May 14 | Oct 2 | 141 d | 6a |
| Mexico | Apr 21 | Oct 24 | 186 d | 7a |
| Meyersdale | May 12 | Oct 5 | 146 d | 6a |
| Middleburg | Apr 27 | Oct 16 | 172 d | 6b |
| Middlebury Center | May 6 | Oct 10 | 157 d | 6a |
| Middleport | Apr 30 | Oct 22 | 175 d | 6b |
| Middletown | Apr 9 | Nov 2 | 207 d | 7a |
| Midland | Apr 28 | Oct 26 | 181 d | 6b |
| Midway | Apr 23 | Oct 23 | 183 d | 6b |
| Mifflin | Apr 21 | Oct 24 | 186 d | 7a |
| Mifflinburg | Apr 25 | Oct 19 | 177 d | 6b |
| Mifflintown | Apr 21 | Oct 24 | 186 d | 7a |
| Mifflinville | May 4 | Oct 11 | 160 d | 6b |
| Milan | May 6 | Oct 10 | 157 d | 6a |
| Milanville | May 3 | Oct 9 | 159 d | 6a |
| Mildred | May 14 | Oct 2 | 141 d | 6a |
| Milesburg | May 21 | Sep 27 | 129 d | 6b |
| Milford | May 2 | Oct 12 | 163 d | 6b |
| Milford Square | Apr 26 | Oct 17 | 174 d | 7a |
| Mill Creek | Apr 19 | Oct 28 | 192 d | 6b |
| Mill Hall | Apr 30 | Oct 20 | 173 d | 6b |
| Mill Run | Apr 22 | Oct 27 | 188 d | 6a |
| Mill Village | May 7 | Oct 10 | 156 d | 6a |
| Millersburg | May 1 | Oct 16 | 168 d | 7a |
| Millerstown | May 1 | Oct 16 | 168 d | 6b |
| Millersville | Apr 1 | Nov 10 | 223 d | 7a |
| Millerton | May 9 | Oct 12 | 156 d | 6a |
| Millheim | May 5 | Oct 6 | 154 d | 6b |
| Millmont | Apr 25 | Oct 19 | 177 d | 6b |
| Millrift | May 2 | Oct 12 | 163 d | 6b |
| Mills | May 20 | Sep 29 | 132 d | 5b |
| Millsboro | May 3 | Oct 15 | 165 d | 6b |
| Millville | May 4 | Oct 11 | 160 d | 6b |
| Milnesville | Apr 30 | Oct 22 | 175 d | 6b |
| Milroy | Apr 21 | Oct 24 | 186 d | 6b |
| Milton | Apr 26 | Oct 20 | 177 d | 6b |
| Mineral Point | Apr 29 | Oct 21 | 175 d | 6a |
| Mineral Springs | May 4 | Oct 11 | 160 d | 6a |
| Minersville | Apr 30 | Oct 22 | 175 d | 6b |
| Mingoville | May 5 | Oct 6 | 154 d | 6b |
| Minisink Hills | May 1 | Oct 12 | 164 d | 6b |
| Modena | Apr 19 | Oct 25 | 189 d | 7a |
| Mohnton | Apr 14 | Oct 29 | 198 d | 7a |
| Mohrsville | Apr 16 | Oct 25 | 192 d | 7a |
| Monaca | Apr 28 | Oct 26 | 181 d | 6b |
| Monessen | Apr 13 | Nov 5 | 206 d | 6b |
| Monongahela | Apr 13 | Nov 5 | 206 d | 6b |
| Monroeton | May 2 | Oct 15 | 166 d | 6a |
| Monroeville | Apr 22 | Oct 25 | 186 d | 6b |
| Mont Alto | Apr 27 | Oct 20 | 176 d | 7a |
| Mont Clare | Apr 18 | Oct 27 | 192 d | 7a |
| Montandon | Apr 26 | Oct 20 | 177 d | 6b |
| Montgomery | Apr 24 | Oct 23 | 182 d | 6b |
| Montgomeryville | Apr 11 | Nov 1 | 204 d | 7a |
| Montoursville | Apr 24 | Oct 23 | 182 d | 6b |
| Montrose | May 14 | Oct 2 | 141 d | 5b |
| Moosic | Apr 23 | Oct 20 | 180 d | 6b |
| Morann | May 13 | Oct 1 | 141 d | 6a |
| Morgan | Apr 23 | Oct 23 | 183 d | 6b |
| Morgantown | Apr 16 | Oct 27 | 194 d | 7a |
| Morris | May 10 | Oct 5 | 148 d | 6a |
| Morris Run | May 16 | Oct 2 | 139 d | 6a |
| Morrisdale | May 13 | Oct 1 | 141 d | 6a |
| Morrisville | Apr 17 | Oct 28 | 194 d | 7a |
| Morton | Apr 2 | Nov 10 | 222 d | 7b |
| Moscow | Apr 23 | Oct 20 | 180 d | 6a |
| Moshannon | May 21 | Sep 27 | 129 d | 6a |
| Mount Aetna | Apr 20 | Oct 25 | 188 d | 7a |
| Mount Bethel | Apr 30 | Oct 18 | 171 d | 6b |
| Mount Braddock | Apr 30 | Oct 18 | 171 d | 6b |
| Mount Carmel | Apr 27 | Oct 20 | 176 d | 6b |
| Mount Gretna | Apr 20 | Oct 25 | 188 d | 7a |
| Mount Holly Springs | Apr 23 | Oct 18 | 178 d | 7a |
| Mount Jewett | May 18 | Oct 1 | 136 d | 5b |
| Mount Joy | Apr 30 | Oct 10 | 163 d | 7a |
| Mount Morris | Apr 28 | Oct 21 | 176 d | 6b |
| Mount Pleasant | May 1 | Oct 13 | 165 d | 6b |
| Mount Pleasant Mills | Apr 25 | Oct 22 | 180 d | 6b |
| Mount Pocono | May 6 | Oct 8 | 155 d | 6a |
| Mount Union | Apr 19 | Oct 28 | 192 d | 7a |
| Mount Wolf | Apr 9 | Nov 2 | 207 d | 7a |
| Mountain Top | May 7 | Oct 6 | 152 d | 6b |
| Mountainhome | May 6 | Oct 8 | 155 d | 6a |
| Mountville | Apr 30 | Oct 10 | 163 d | 7a |
| Muir | May 1 | Oct 16 | 168 d | 6b |
| Muncy | Apr 24 | Oct 23 | 182 d | 6b |
| Muncy Valley | May 6 | Oct 7 | 154 d | 6a |
| Munson | May 13 | Oct 1 | 141 d | 6a |
| Murrysville | Apr 22 | Oct 25 | 186 d | 6b |
| Muse | Apr 24 | Oct 23 | 182 d | 6b |
| Myerstown | Apr 20 | Oct 25 | 188 d | 7a |