Frequently the average temperatures in Cayo Guillermo in December is 21. You can expect highs around 28 with low of 18 celsius. We have put some more information here:
| Month | Degrees Celsius |
|---|---|
| Temperature | 21 |
| High Temperature | 28 |
| Low Temperature | 18 |
| Sunshine Per Day | 8 |
Useful Links: Cayo Guillermo Weather: Average Weather & Yearly Climate