Wisconsin frost dates: I
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Independence | May 9 | Oct 1 | 145 d | 4b |
| Iola | May 8 | Oct 6 | 151 d | 5a |
| Irma | May 11 | Sep 30 | 142 d | 4b |
| Iron Belt | May 24 | Sep 28 | 127 d | 4a |
| Iron Ridge | Apr 28 | Oct 10 | 165 d | 5a |
| Iron River | May 24 | Sep 26 | 125 d | 4a |
| Ixonia | Apr 30 | Oct 12 | 165 d | 5a |