Utah frost dates: R
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Randlett | May 2 | Oct 3 | 154 d | 5b |
| Randolph | Jun 14 | Sep 1 | 79 d | 4a |
| Redmond | May 21 | Sep 24 | 126 d | 6a |
| Richfield | May 21 | Sep 24 | 126 d | 6a |
| Richmond | May 11 | Oct 5 | 147 d | 6a |
| Riverside | Apr 24 | Oct 17 | 176 d | 6b |
| Riverton | Apr 18 | Oct 22 | 187 d | 7a |
| Rockville | Apr 13 | Nov 2 | 203 d | 8a |
| Roosevelt | May 23 | Sep 22 | 122 d | 5b |
| Roy | Apr 22 | Oct 22 | 183 d | 7a |
| Rush Valley | May 15 | Oct 5 | 143 d | 6a |