The North of Spain is colder than the South, and in the interior it usually snows.
Although in the Mediterranean coast, does not snow, it's cold but not as much as to snow, and many days are sunny but shorter than in summer.
In winter, beach towns are with very few people, although big cities and interior cities are full of people.
There is still nightlife but only in big cities and on fridays and saturdays night.
You can find information in this link: http://www.aemet.es/en/eltiempo/predicci...
The only places that might be slightly warm are on the Mediterranean coast.
The Meseta, which is the high plateau which covers two-thirds of Spain and includes Madrid, will be freezing, windy and snowy. The Northern coastal areas will be cold and rainy. And the ski resorts near Granada, Barcelona, the Pyrenees, and other mountain areas will be thriving.
Depends which part but Costa Blanca(Benidorm) is still slighty warm in December and a lot of pensioners go there for 6 weeks winter season or Costa Del Sol warm/cool but the Costa Brava or Majorca/Ibiza close down around October for the winter and it is cold and can snow, Canary islands are still warm during the winter.
Very cold and snowy inland and in the mountains.
Wet and miserable everywhere else.
I've been to Barcelona in the winter, it was cool. There were Christmas lights everywhere and lots of people in the city!
Cooler than it is in the summer.
