Kansas frost dates: O
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Oakley | May 6 | Oct 9 | 156 d | 6a |
| Oberlin | Apr 30 | Oct 11 | 164 d | 6a |
| Offerle | Apr 20 | Oct 20 | 183 d | 6b |
| Ogallah | Apr 23 | Oct 18 | 178 d | 6b |
| Ogden | Apr 21 | Oct 16 | 178 d | 6b |
| Oketo | Apr 25 | Oct 13 | 171 d | 6a |
| Olathe | Apr 10 | Oct 29 | 202 d | 6b |
| Olmitz | Apr 24 | Oct 15 | 174 d | 6b |
| Olpe | Apr 12 | Oct 23 | 194 d | 6b |
| Olsburg | Apr 22 | Oct 20 | 181 d | 6a |
| Onaga | Apr 19 | Oct 19 | 183 d | 6a |
| Oneida | Apr 22 | Oct 13 | 174 d | 6a |
| Opolis | Apr 7 | Oct 30 | 206 d | 7a |
| Osage City | Apr 13 | Oct 26 | 196 d | 6b |
| Osawatomie | Apr 14 | Oct 25 | 194 d | 6b |
| Osborne | Apr 29 | Oct 12 | 166 d | 6a |
| Oskaloosa | Apr 16 | Oct 22 | 189 d | 6b |
| Oswego | Apr 11 | Oct 26 | 198 d | 7a |
| Otis | Apr 30 | Oct 10 | 163 d | 6b |
| Ottawa | Apr 18 | Oct 20 | 185 d | 6b |
| Overbrook | Apr 8 | Oct 31 | 206 d | 6b |
| Overland Park | Apr 10 | Oct 29 | 202 d | 6b |
| Oxford | Apr 11 | Oct 27 | 199 d | 7a |
| Ozawkie | Apr 10 | Oct 29 | 202 d | 6b |