Don't worry about the weather too much, in Lisbon the sun is usually shinning. In this list you'll find the best views in Lisbon: viewpoints, or "miradouros" as we say in Portuguese, terraces, by the shore or from the river. A sunrise you won't want to miss.
The best places to see the sunrise in Lisbon
By the river
The Cais das Colunas, the quay on the river at Terreiro do Paço (Praça de Comércio), affords a clear view east that is perfect for seeing the the sun king ascend his throne. In fact, all along the riverbank to Belém, is a good place to see the sun rise. But it is at Cais do Sodré boat station, just where you board the ferry, that is the best place to appreciate the sunrise – not least because it is near some of Lisbon’s best nightclubs.
From a miradouro
Unfortunately, few of Lisbon’s many viewpoints are turned to the east. But there is one that is 60% suitable and another that makes 100%. The São Pedro de Alcântara garden, next to the Bairro Alto, faces the right way, but the rising sun is hidden by the castle; the viewing platform at Largo das Portas do Sol, at the top of Alfama, is a great place to see the day dawn.
On a ferry
When the sun starts to edge its way over the horizon, the best place to be is right in the middle of the Tagus – preferably floating above the surface. So board one fo the ferries that do the trip from Cais do Sodré to Cacilhas (and then come back to Lisbon, of course).