Arizona frost dates: R
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Red Rock | Feb 6 | Dec 9 | 306 d | 9a |
| Red Valley | May 22 | Oct 8 | 139 d | 7a |
| Rillito | Feb 23 | Dec 6 | 286 d | 9b |
| Rimrock | Apr 16 | Oct 30 | 197 d | 8a |
| Rio Rico | Apr 5 | Nov 10 | 219 d | 8b |
| Rio Verde | Jan 6 | Dec 28 | 356 d | 9b |
| Rock Point | May 3 | Oct 17 | 167 d | 7a |
| Roll | Feb 13 | Dec 1 | 291 d | 9b |
| Roosevelt | Jan 17 | Dec 25 | 342 d | 9b |
| Round Rock | May 3 | Oct 17 | 167 d | 7a |