Montana frost dates: D
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Dagmar | May 16 | Sep 18 | 125 d | 3b |
| Darby | May 24 | Sep 23 | 122 d | 5b |
| Dayton | May 1 | Oct 15 | 167 d | 6a |
| De Borgia | frost any month | 6a | ||
| Decker | May 18 | Sep 24 | 129 d | 5a |
| Deer Lodge | frost any month | 4b | ||
| Dell | Jun 11 | Sep 10 | 91 d | 5a |
| Denton | Jun 1 | Sep 11 | 102 d | 4b |
| Dillon | Jun 5 | Sep 13 | 100 d | 5a |
| Divide | Jun 10 | Sep 7 | 89 d | 5a |
| Dixon | May 12 | Oct 2 | 143 d | 6a |
| Dodson | May 10 | Sep 29 | 142 d | 4a |
| Drummond | frost any month | 5b | ||
| Dupuyer | Jun 9 | Sep 3 | 86 d | 4b |
| Dutton | May 20 | Sep 22 | 125 d | 4a |