Pennsylvania frost dates: I
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Ickesburg | Apr 18 | Oct 26 | 191 d | 6b |
| Idaville | Apr 15 | Oct 27 | 195 d | 7a |
| Imler | Apr 29 | Oct 13 | 167 d | 6b |
| Immaculata | Apr 19 | Oct 26 | 190 d | 7a |
| Imperial | Apr 23 | Oct 23 | 183 d | 6b |
| Indian Head | Apr 30 | Oct 17 | 170 d | 6a |
| Indiana | May 8 | Oct 13 | 158 d | 6b |
| Indianola | Apr 16 | Nov 1 | 199 d | 6b |
| Industry | Apr 28 | Oct 26 | 181 d | 6b |
| Ingomar | Apr 24 | Oct 27 | 186 d | 6b |
| Intercourse | Apr 14 | Nov 1 | 201 d | 7a |
| Irvine | May 4 | Oct 21 | 170 d | 6a |
| Irvona | May 10 | Oct 5 | 148 d | 6a |
| Irwin | Apr 22 | Oct 25 | 186 d | 6b |
| Isabella | Apr 28 | Oct 21 | 176 d | 6b |