Oklahoma frost dates: O
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Oakhurst | Mar 30 | Nov 4 | 219 d | 7b |
| Oaks | Mar 31 | Nov 2 | 216 d | 7a |
| Oakwood | Apr 6 | Nov 3 | 211 d | 7a |
| Ochelata | Mar 31 | Oct 31 | 214 d | 7a |
| Oilton | Apr 6 | Oct 29 | 206 d | 7a |
| Okarche | Apr 9 | Nov 1 | 206 d | 7b |
| Okay | Apr 7 | Oct 30 | 206 d | 7b |
| Okeene | Apr 7 | Nov 2 | 209 d | 7a |
| Okemah | Mar 24 | Nov 9 | 230 d | 7b |
| Oklahoma City | Apr 2 | Nov 5 | 217 d | 7b |
| Okmulgee | Apr 8 | Oct 28 | 203 d | 7b |
| Oktaha | Apr 2 | Nov 2 | 214 d | 7b |
| Olustee | Apr 3 | Nov 4 | 215 d | 7b |
| Omega | Apr 14 | Oct 27 | 196 d | 7b |
| Oologah | Apr 7 | Oct 30 | 206 d | 7a |
| Orlando | Apr 10 | Oct 25 | 198 d | 7a |
| Osage | Apr 6 | Oct 29 | 206 d | 7b |
| Oscar | Mar 23 | Nov 7 | 229 d | 8a |
| Overbrook | Mar 15 | Nov 14 | 244 d | 8a |
| Owasso | Mar 31 | Nov 4 | 218 d | 7b |