Colorado frost dates: F
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Fairplay | Jun 16 | Sep 9 | 85 d | 5b |
| Firestone | May 7 | Oct 5 | 151 d | 5b |
| Flagler | May 5 | Oct 8 | 156 d | 5b |
| Fleming | May 4 | Oct 11 | 160 d | 5b |
| Florence | May 4 | Oct 7 | 156 d | 6a |
| Florissant | frost any month | 5a | ||
| Fort Collins | May 2 | Oct 7 | 158 d | 5b |
| Fort Garland | May 25 | Sep 22 | 120 d | 5b |
| Fort Lupton | May 3 | Oct 7 | 157 d | 5b |
| Fort Lyon | Apr 29 | Oct 12 | 166 d | 6a |
| Fort Morgan | May 6 | Oct 6 | 153 d | 5b |
| Fountain | May 3 | Oct 8 | 158 d | 6a |
| Fowler | May 5 | Oct 6 | 154 d | 6a |
| Franktown | May 16 | Oct 2 | 139 d | 5b |
| Fraser | frost any month | 5b | ||
| Frederick | May 7 | Oct 5 | 151 d | 5b |
| Frisco | frost any month | 5a | ||
| Fruita | Apr 27 | Oct 11 | 167 d | 7a |