Wisconsin frost dates: S
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Saint Cloud | May 3 | Oct 10 | 160 d | 5b |
| Saint Croix Falls | May 19 | Sep 25 | 129 d | 4a |
| Saint Francis | Apr 19 | Oct 29 | 193 d | 6a |
| Saint Germain | May 19 | Oct 3 | 137 d | 4a |
| Saint Nazianz | May 1 | Oct 14 | 166 d | 5b |
| Salem | Apr 30 | Oct 15 | 168 d | 5b |
| Sand Creek | May 10 | Sep 29 | 142 d | |
| Sarona | May 14 | Sep 28 | 137 d | 4a |
| Sauk City | May 4 | Oct 6 | 155 d | 5a |
| Saukville | May 5 | Oct 11 | 159 d | 5b |
| Saxeville | May 8 | Oct 6 | 151 d | 5a |
| Saxon | May 23 | Oct 1 | 131 d | 4b |
| Sayner | May 19 | Oct 3 | 137 d | 4b |
| Scandinavia | May 8 | Oct 6 | 151 d | 5a |
| Schofield | May 6 | Oct 4 | 151 d | 4b |
| Seneca | May 3 | Oct 7 | 157 d | 5a |
| Sextonville | May 5 | Oct 6 | 154 d | 4b |
| Seymour | May 1 | Oct 11 | 163 d | 5a |
| Sharon | Apr 30 | Oct 10 | 163 d | 5b |
| Shawano | May 9 | Oct 2 | 146 d | 5a |
| Sheboygan | Apr 25 | Oct 23 | 181 d | 6a |
| Sheboygan Falls | May 5 | Oct 8 | 156 d | 5b |
| Sheldon | May 20 | Sep 23 | 126 d | 4a |
| Shell Lake | May 14 | Sep 28 | 137 d | 4a |
| Sherwood | May 6 | Oct 6 | 153 d | 5b |
| Shiocton | May 4 | Oct 6 | 155 d | 5a |
| Shullsburg | May 3 | Oct 4 | 154 d | 5a |
| Silver Lake | Apr 30 | Oct 15 | 168 d | 5b |
| Sinsinawa | Apr 19 | Oct 21 | 185 d | 5a |
| Siren | May 11 | Oct 1 | 143 d | 4b |
| Sister Bay | May 14 | Oct 18 | 157 d | 5b |
| Slinger | May 5 | Oct 5 | 153 d | 5a |
| Sobieski | May 7 | Oct 9 | 155 d | 5a |
| Soldiers Grove | May 3 | Oct 7 | 157 d | 5a |
| Solon Springs | May 12 | Oct 2 | 143 d | 4a |
| Somers | Apr 28 | Oct 19 | 174 d | 5b |
| Somerset | Apr 22 | Oct 19 | 180 d | 4b |
| South Milwaukee | Apr 22 | Oct 26 | 187 d | 6a |
| South Range | May 18 | Oct 3 | 138 d | 4b |
| South Wayne | Apr 27 | Oct 14 | 170 d | 5a |
| Sparta | May 9 | Oct 1 | 145 d | 4b |
| Spencer | May 5 | Oct 5 | 153 d | 4b |
| Spooner | May 14 | Sep 28 | 137 d | 4a |
| Spring Green | Apr 30 | Oct 9 | 162 d | 5a |
| Spring Valley | May 6 | Oct 2 | 149 d | 4b |
| Springbrook | May 22 | Sep 23 | 124 d | 4a |
| Springfield | Apr 25 | Oct 21 | 179 d | 5b |
| Stanley | May 7 | Oct 3 | 149 d | 4b |
| Star Lake | May 19 | Oct 3 | 137 d | 4b |
| Star Prairie | May 5 | Oct 4 | 152 d | 4b |
| Stetsonville | May 11 | Oct 1 | 143 d | 4b |
| Steuben | Apr 22 | Oct 20 | 181 d | 5a |
| Stevens Point | May 4 | Oct 7 | 156 d | 5a |
| Stitzer | Apr 27 | Oct 11 | 167 d | 5a |
| Stockbridge | May 1 | Oct 14 | 166 d | 5b |
| Stockholm | May 1 | Oct 10 | 162 d | 4b |
| Stoddard | Apr 22 | Oct 17 | 178 d | 5a |
| Stone Lake | frost any month | 4a | ||
| Stoughton | Apr 30 | Oct 11 | 164 d | 5b |
| Stratford | May 5 | Oct 5 | 153 d | 4b |
| Strum | May 10 | Oct 2 | 145 d | 4b |
| Sturgeon Bay | May 8 | Oct 13 | 158 d | 5b |
| Sturtevant | Apr 20 | Oct 24 | 187 d | 5b |
| Suamico | May 7 | Oct 9 | 155 d | 5b |
| Sullivan | May 3 | Oct 9 | 159 d | 5b |
| Summit Lake | Jun 3 | Sep 18 | 107 d | 4b |
| Sun Prairie | May 1 | Oct 10 | 162 d | 5a |
| Superior | May 6 | Oct 9 | 156 d | 4b |
| Suring | May 14 | Oct 1 | 140 d | 5a |
| Sussex | Apr 30 | Oct 16 | 169 d | 5b |