Wisconsin frost dates: R
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Racine | Apr 20 | Oct 24 | 187 d | 6a |
| Radisson | May 19 | Sep 27 | 131 d | 4a |
| Randolph | May 1 | Oct 11 | 163 d | 5a |
| Random Lake | May 3 | Oct 16 | 166 d | 5b |
| Readfield | May 4 | Oct 6 | 155 d | 5a |
| Readstown | May 7 | Oct 2 | 148 d | 5a |
| Redgranite | May 1 | Oct 8 | 160 d | 5a |
| Reedsburg | Apr 24 | Oct 20 | 179 d | 5a |
| Reedsville | May 6 | Oct 6 | 153 d | 5b |
| Reeseville | May 2 | Oct 9 | 160 d | 5b |
| Rewey | Apr 30 | Oct 13 | 166 d | 5a |
| Rhinelander | May 23 | Sep 23 | 123 d | 4b |
| Rib Lake | May 11 | Oct 1 | 143 d | 4a |
| Rice Lake | May 8 | Oct 2 | 147 d | 4b |
| Richfield | Apr 30 | Oct 15 | 168 d | 5b |
| Richland Center | May 5 | Oct 6 | 154 d | 5a |
| Ridgeland | May 10 | Sep 29 | 142 d | 4b |
| Ridgeway | May 3 | Oct 7 | 157 d | 5a |
| Ringle | May 6 | Oct 4 | 151 d | 4b |
| Rio | May 4 | Oct 6 | 155 d | 5a |
| Ripon | May 1 | Oct 11 | 163 d | 5a |
| River Falls | May 11 | Oct 1 | 143 d | 4b |
| Roberts | May 6 | Oct 2 | 149 d | 4b |
| Rochester | May 5 | Oct 10 | 158 d | 5b |
| Rock Falls | Apr 24 | Oct 14 | 173 d | 4b |
| Rock Springs | Apr 24 | Oct 20 | 179 d | 5a |
| Rockland | May 9 | Oct 1 | 145 d | 5a |
| Rosendale | May 1 | Oct 10 | 162 d | 5a |
| Rosholt | May 6 | Oct 5 | 152 d | 4b |
| Rothschild | May 6 | Oct 4 | 151 d | 5a |
| Rubicon | May 8 | Oct 3 | 148 d | 5a |
| Rudolph | May 9 | Sep 30 | 144 d | 4b |