Oregon frost dates: R
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Rainier | Apr 8 | Nov 5 | 211 d | 8b |
| Redmond | Jun 9 | Sep 14 | 97 d | 6b |
| Reedsport | Mar 25 | Nov 24 | 244 d | 9a |
| Rhododendron | May 27 | Oct 9 | 135 d | 7b |
| Richland | May 10 | Oct 1 | 144 d | 6b |
| Rickreall | Apr 16 | Nov 1 | 199 d | 8b |
| Riddle | Mar 31 | Nov 6 | 220 d | 8b |
| Riley | Jun 11 | Sep 28 | 109 d | 6a |
| Riverside | Jun 7 | Sep 6 | 91 d | 6a |
| Rockaway Beach | Apr 22 | Oct 21 | 182 d | 9a |
| Rogue River | Apr 8 | Oct 28 | 203 d | 8b |
| Roseburg | Mar 23 | Nov 18 | 240 d | 8b |
| Rufus | May 19 | Sep 25 | 129 d | 8a |