Idaho frost dates: A
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Aberdeen | May 21 | Sep 20 | 122 d | 5b |
| Ahsahka | Apr 20 | Oct 20 | 183 d | 7a |
| Albion | Jun 5 | Sep 13 | 100 d | 6b |
| Almo | May 15 | Oct 2 | 140 d | 6a |
| American Falls | May 20 | Sep 26 | 129 d | 6a |
| Arbon | May 23 | Sep 24 | 124 d | 6a |
| Arco | May 22 | Sep 22 | 123 d | 5a |
| Arimo | May 23 | Sep 24 | 124 d | 6b |
| Ashton | May 21 | Sep 21 | 123 d | 5a |
| Athol | May 22 | Sep 22 | 123 d | 6b |
| Atlanta | Jun 6 | Sep 4 | 90 d | |
| Atomic City | Jun 11 | Sep 6 | 87 d | |
| Avery | May 12 | Sep 30 | 141 d | 6b |