Montana frost dates: G
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Galata | May 23 | Sep 14 | 114 d | 4a |
| Gallatin Gateway | frost any month | 5a | ||
| Gardiner | May 21 | Sep 27 | 129 d | 4b |
| Garrison | frost any month | 4b | ||
| Garryowen | May 13 | Sep 29 | 139 d | 4b |
| Geraldine | May 14 | Sep 26 | 135 d | 4b |
| Geyser | May 22 | Sep 23 | 124 d | 4b |
| Gildford | May 24 | Sep 15 | 114 d | 3b |
| Glasgow | May 6 | Sep 30 | 147 d | 4a |
| Glen | frost any month | 4b | ||
| Glendive | May 3 | Oct 4 | 154 d | 4a |
| Glentana | Jun 5 | Sep 2 | 89 d | 3b |
| Gold Creek | frost any month | 4b | ||
| Grantsdale | May 21 | Sep 22 | 124 d | 5b |
| Grass Range | May 20 | Sep 24 | 127 d | 4b |
| Great Falls | May 6 | Oct 1 | 148 d | 4b |
| Greycliff | May 14 | Sep 26 | 135 d | 5a |