North Carolina frost dates: O
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Oak City | Mar 29 | Nov 7 | 223 d | 8a |
| Oak Island | Mar 24 | Nov 17 | 238 d | 8b |
| Oak Ridge | Mar 30 | Nov 5 | 220 d | 8a |
| Oakboro | Mar 29 | Nov 4 | 220 d | 8a |
| Ocean Isle Beach | Mar 20 | Nov 17 | 242 d | 8b |
| Ocracoke | Mar 1 | Dec 20 | 294 d | 9a |
| Old Fort | Apr 21 | Oct 23 | 185 d | 7b |
| Olin | Apr 16 | Oct 25 | 192 d | 7b |
| Olivia | Apr 10 | Oct 30 | 203 d | 8a |
| Oriental | Mar 30 | Nov 8 | 223 d | 8b |
| Orrum | Apr 1 | Nov 5 | 218 d | 8b |
| Otto | Apr 23 | Oct 17 | 177 d | 7b |
| Oxford | Mar 30 | Nov 6 | 221 d | 7b |