Oregon frost dates: H
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Haines | May 25 | Sep 15 | 113 d | 6a |
| Halfway | May 15 | Sep 24 | 132 d | 6b |
| Halsey | Apr 11 | Oct 30 | 202 d | 8b |
| Hammond | Mar 26 | Nov 11 | 230 d | 9a |
| Happy Valley | Mar 18 | Nov 18 | 245 d | 8b |
| Harper | May 7 | Oct 3 | 149 d | 6b |
| Harrisburg | Apr 11 | Oct 23 | 195 d | 8b |
| Hebo | Mar 17 | Nov 22 | 250 d | 8b |
| Helix | May 12 | Sep 27 | 138 d | 7a |
| Heppner | Apr 26 | Oct 19 | 176 d | 7a |
| Hereford | frost any month | 6a | ||
| Hermiston | Apr 27 | Oct 7 | 163 d | 7b |
| Hillsboro | Apr 16 | Oct 23 | 190 d | 8b |
| Hines | Jun 11 | Sep 6 | 87 d | 6a |
| Hood River | Apr 20 | Oct 13 | 176 d | 7b |
| Hubbard | Mar 16 | Nov 14 | 243 d | 8b |
| Huntington | Apr 23 | Oct 13 | 173 d | 7a |