Maryland frost dates: R
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Randallstown | Apr 2 | Nov 7 | 219 d | 7a |
| Rawlings | Apr 30 | Oct 15 | 168 d | 7a |
| Rehobeth | Mar 31 | Nov 11 | 225 d | 7b |
| Reisterstown | Apr 2 | Nov 7 | 219 d | 7a |
| Rhodesdale | Apr 8 | Nov 4 | 210 d | 7b |
| Riderwood | Apr 2 | Nov 7 | 219 d | 7b |
| Ridge | Mar 30 | Nov 14 | 229 d | 8a |
| Ridgely | Apr 11 | Oct 30 | 202 d | 7b |
| Rising Sun | Apr 3 | Nov 6 | 217 d | 7a |
| Riva | Mar 27 | Nov 13 | 231 d | 7b |
| Riverdale | Mar 29 | Nov 8 | 224 d | 7b |
| Rock Hall | Apr 3 | Nov 5 | 216 d | 8a |
| Rock Point | Apr 17 | Oct 27 | 193 d | 8a |
| Rockville | Apr 1 | Nov 6 | 219 d | 7b |
| Rocky Ridge | Apr 22 | Oct 20 | 181 d | 7a |
| Rohrersville | Apr 26 | Oct 18 | 175 d | 7a |
| Rosedale | Mar 24 | Nov 21 | 242 d | 8a |
| Royal Oak | Apr 1 | Nov 7 | 220 d | 8a |