Iowa frost dates: D
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Dakota City | Apr 26 | Oct 12 | 169 d | 5a |
| Dallas Center | Apr 25 | Oct 10 | 168 d | 5b |
| Dana | Apr 26 | Oct 9 | 166 d | 5a |
| Danbury | May 3 | Oct 1 | 151 d | 5a |
| Danville | Apr 15 | Oct 20 | 188 d | 6a |
| Davenport | Apr 23 | Oct 15 | 175 d | 5b |
| Davis City | Apr 16 | Oct 21 | 188 d | 5b |
| Dawson | Apr 25 | Oct 10 | 168 d | 5a |
| Dayton | Apr 28 | Oct 12 | 167 d | 5a |
| De Soto | Apr 30 | Oct 3 | 156 d | 5b |
| De Witt | Apr 22 | Oct 16 | 177 d | 5b |
| Decatur | Apr 16 | Oct 21 | 188 d | 5b |
| Decorah | May 3 | Oct 7 | 157 d | 5a |
| Dedham | Apr 27 | Oct 10 | 166 d | 5a |
| Deep River | Apr 24 | Oct 15 | 174 d | 5b |
| Defiance | Apr 27 | Oct 9 | 165 d | 5a |
| Delaware | May 3 | Oct 4 | 154 d | 4b |
| Delhi | May 3 | Oct 4 | 154 d | 5a |
| Delmar | Apr 25 | Oct 14 | 172 d | 5a |
| Deloit | Apr 27 | Oct 11 | 167 d | 5a |
| Delta | Apr 24 | Oct 15 | 174 d | 5b |
| Denison | Apr 27 | Oct 11 | 167 d | 5a |
| Denmark | Apr 12 | Oct 25 | 196 d | 6a |
| Denver | Apr 27 | Oct 10 | 166 d | 5a |
| Derby | May 5 | Oct 5 | 153 d | 5b |
| Des Moines | Apr 23 | Oct 15 | 175 d | 5b |
| Dewar | Apr 27 | Oct 10 | 166 d | 5a |
| Dexter | Apr 30 | Oct 3 | 156 d | 5b |
| Diagonal | Apr 25 | Oct 12 | 170 d | 5b |
| Dickens | May 1 | Oct 3 | 155 d | 5a |
| Dike | Apr 29 | Oct 9 | 163 d | 5a |
| Dixon | Apr 23 | Oct 15 | 175 d | 5b |
| Dolliver | May 2 | Sep 30 | 151 d | 5a |
| Donahue | Apr 23 | Oct 15 | 175 d | 5b |
| Donnellson | Apr 17 | Oct 22 | 188 d | 6a |
| Doon | May 1 | Oct 4 | 156 d | 5a |
| Dorchester | May 2 | Oct 11 | 162 d | 5a |
| Douds | Apr 26 | Oct 13 | 170 d | 5b |
| Dougherty | Apr 29 | Oct 9 | 163 d | 5a |
| Dow City | Apr 27 | Oct 11 | 167 d | 5a |
| Dows | Apr 30 | Oct 10 | 163 d | 5a |
| Drakesville | Apr 16 | Oct 22 | 189 d | 5b |
| Dubuque | Apr 19 | Oct 21 | 185 d | 5a |
| Dumont | Apr 27 | Oct 8 | 164 d | 5a |
| Duncombe | Apr 28 | Oct 8 | 163 d | 5a |
| Dundee | May 3 | Oct 4 | 154 d | 5a |
| Dunkerton | Apr 27 | Oct 10 | 166 d | 5a |
| Dunlap | Apr 29 | Oct 8 | 162 d | 5b |
| Durango | Apr 19 | Oct 21 | 185 d | 5a |
| Durant | Apr 18 | Oct 22 | 187 d | 5b |
| Dyersville | Apr 28 | Oct 10 | 165 d | 5a |
| Dysart | May 3 | Oct 3 | 153 d | 5a |