[cfn]

Inland Portugal can be freezing cold in the Winter, we got -2 C several days in a row last year (I know, -2 C is balmy elsewhere but try it without central heating). You should be okay if you stick to the coast as the sea breezes keep the temperatures in the 10-15 C most of the time.

[toomanybeersies]

If you've got a good sleeping bag, -2 C isn't that bad. I've spent the night with those temperatures in the high country of New Zealand. I know people that have spent the night in -15 C temperatures.

[cfn]

That may be OK for sleeping but it is very hard to work. I spent a couple of Winters coding without heating with indoor temperatures around 12 Celsius and it was very hard. I wore mittens, bubble hat, a blanket and even an electric foot warmer and still had to stop working and walk a bit every now and then to warm up.

[toomanybeersies]

Yeah, I had to live through that as well when I was at university. Fingerless gloves were essential. Below 15 C, it actually gets hard to type.

[jvzr]

What's a bubble hat, if I may ask?

[cfn]

Sorry, bobble hat. It is a wool hat with a wool "ball" at the top. Search google images for wool bobble hat.