Coming to the south Portugal we all expect to have warm sunny days. And its true! After -5C in Ukraine I came on 17th of January to Algarve, the warmest region in Portugal, and took off my light Autumn coat, having +23C. I remember that day very good - Hungarian volunteer Lisy met me just in t-shirt. I was feeling so good, warming myself on the sun. We had sun in winter almost every day and for the whole day. Having so much sun was like a paradise for me. We even based in the ocean in the super cold water.
BUT, not all days are so warm and there is no central heating inside houses. So, in winter, at daytime it's colder inside the buildings than outside. It's a problem, especially, when rooms are not on the sun side. For me and Lisy it was hard to get used to coldness at home, so we used electric heaters a lot.