Usually the weather in Lisbon all through December is 10. You can expect highs around 15 with lows around 8 degrees celsius. We have put some more info below:
| Month | Degrees Celsius |
|---|---|
| Temperature | 10 |
| High Temperature | 15 |
| Low Temperature | 8 |
| Sunshine Per Day | 5 |
Useful Links: Lisbon Weather: Average Weather & Yearly Climate