You mean the northwest like Galicia? The northeast where I live still gets plenty hot. We don't have major beach resorts like Lloret and Salou for no reason :)
Though I guess this might not qualify as "Spain" depending on who you ask - if I ask my neighbours if they are living in Spain they certainly will say NO :P Hot topic alert :)
The Atlantic Spain and everything around Picos de Europa. Also, most mountain ranges, and Spain is the 2nd most mountainous country in Europe, so a lot of Spain is not that warm in Winter.
Though I guess this might not qualify as "Spain" depending on who you ask - if I ask my neighbours if they are living in Spain they certainly will say NO :P Hot topic alert :)