Galicia & AsturiasThe cities of Santiago de Compostela and A Coruña in Galicia and Oviedo in Asturias are the greenest parts of Spain - and for green, you need rain. Good for ducks and good for those who don't like the extreme cold - the damp weather and proximity to the coast means it rarely gets as cold as Salamanca & Burgos, despite being further north. Nor does it ever get too hot, either. During the year, the average monthly temperature in Oviedo varies between 8ºC and 18ºC (46ºF and 64ºF).
The north coast of Spain should be popular with Brits - like with the UK, the Atlantic brings this region some quite grim weather at times. However, this doesn't necessarily mean cold - average temperatures in winter are a couple of degrees higher than in Madrid in Granada. In the summer the weather is warm but nowhere near the temperatures of the south.
The coldest region in Spain, you're as far north as you can get before the warming effect of the sea comes into force. In nearby Burgos the average winter temperature is just 2ºC (35ºF). Summer temperatures are warm and pleasant, but this is not a place to go to get a tan.