West Virginia frost dates: O
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Oak Hill | Apr 21 | Oct 19 | 181 d | 6b |
| Oceana | Apr 22 | Oct 24 | 185 d | 7a |
| Odd | Apr 24 | Oct 20 | 179 d | 6b |
| Old Fields | Apr 29 | Oct 15 | 169 d | 6b |
| Omar | Apr 8 | Nov 2 | 208 d | 7a |
| Ona | Apr 8 | Nov 1 | 207 d | 7a |
| Onego | Apr 30 | Oct 11 | 164 d | 6a |
| Orgas | Apr 7 | Nov 4 | 211 d | 7a |
| Orlando | Apr 26 | Oct 23 | 180 d | 6b |
| Orma | Apr 29 | Oct 19 | 173 d | 6b |
| Osage | Apr 26 | Oct 23 | 180 d | 6b |
| Ottawa | Apr 16 | Oct 27 | 194 d | 7a |