Oregon frost dates: I
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Idanha | May 15 | Sep 30 | 138 d | 7b |
| Idleyld Park | Apr 27 | Oct 19 | 175 d | 8b |
| Imbler | May 24 | Sep 18 | 117 d | 6b |
| Imnaha | Jun 8 | Sep 5 | 89 d | 6b |
| Independence | Apr 16 | Nov 1 | 199 d | 8b |
| Ione | Apr 26 | Oct 19 | 176 d | 7b |
| Ironside | May 7 | Oct 3 | 149 d | 6a |
| Irrigon | Apr 14 | Oct 21 | 190 d | 7b |