Idaho frost dates: F
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Fairfield | Jun 8 | Sep 14 | 98 d | 6a |
| Felt | Jun 15 | Sep 7 | 84 d | 5a |
| Fenn | May 9 | Oct 3 | 147 d | 6b |
| Ferdinand | May 6 | Oct 13 | 160 d | 6a |
| Fernwood | May 3 | Oct 4 | 154 d | 6b |
| Filer | Apr 25 | Oct 15 | 173 d | 7a |
| Firth | May 5 | Oct 3 | 151 d | 5b |
| Fish Haven | May 15 | Oct 4 | 142 d | 5b |
| Fort Hall | May 20 | Sep 20 | 123 d | 5b |
| Franklin | May 16 | Sep 28 | 135 d | 6a |
| Fruitland | Apr 22 | Oct 9 | 170 d | 7a |