California frost dates: J
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Jackson | Mar 4 | Dec 11 | 282 d | 9b |
| Jacumba | Apr 29 | Nov 1 | 186 d | 9b |
| Jamestown | Apr 9 | Nov 9 | 214 d | 9b |
| Jamul | Jan 6 | Dec 21 | 349 d | 10a |
| Janesville | May 16 | Oct 8 | 145 d | 7a |
| Jenner | Feb 26 | Dec 27 | 304 d | 10a |
| Johannesburg | Mar 19 | Nov 25 | 251 d | 9a |
| Jolon | Feb 23 | Nov 22 | 272 d | 9a |
| Joshua Tree | Feb 28 | Dec 1 | 276 d | 9a |
| Julian | Mar 27 | Dec 1 | 249 d | 9b |
| Junction City | May 3 | Oct 11 | 161 d | 8b |
| June Lake | Jun 10 | Sep 17 | 99 d | 6a |