Hi, first post, I used to live in Tenerife, I'm back in the UK for family reasons, but intend to head back to Tenerife, or at least Southern Spain for January February 2014. My favoured mode of transport is my Harley, in fact it's my only mode of transport as I don't own a car.
I've done the journey from Huelva Spain, to the UK 3 times on my bike, going the most direct route of Seville, Madrid, Santander, then France, Biarritz, Le Mans, and on to Calais for the tunnel. Last time was February this year, and it was cold with snow on the mountains, almost unridable in places.
When I go back this coming winter my intention is to go to Santander via ferry from Portsmouth.
Does anyone know if it is possible to follow the coast along northern Spain and into Portugal, then follow the coast along Portugal, to avoid the mountain ranges? I've looked online on a couple of maps, but it doesn't show the contours too well, it would be much better to hear from someone who has already ridden / driven this route.

Thanks in advance.

I have driven the coast from Portugal only as far as A Coruna. The coast line is extremely crenellated, which means the journey takes many extra hours, plus it is extremely stormy, so even it you didnt get snow, you might find riding a Harely out of the question because slick, twisty roads.

Have you looked on Google Earth? You should be able to get a very good view of the terrain using the satellite feature.

Also, you should ask your questions on a bikers forum.

Thanks Steve, I hadn't counted on storms, just wanted to avoid the elevation. I have looked on google earth, but wanted a first hand account really.

I have posted on my normal Harley forum.

I live slightly inland of Galicia. I try and get back to friends and family in The Netherlands every year. Sometimes I have done this trip in winter.
The main A8 (and in parts the N road as not all of the A8 is finished) is usually drivable, with no snow. However it still gets cold and at times can rain a lot.
The road between Galician and Cantabria is in between the mountains and the coast. After that (in The Basque country) it heads up into the Pyrenees. Not the top but quite high.
If you went inland it can get very cold with heavy night frosts.
Weather is going to be unpredictable, unfortunately.

Yep I've done the Basque country 3 times, some fantastic roads in the summer. Perfect for cruising. Not so nice in the winter. It's exactly these I want to avoid by sticking to the coast.
Sounds like the road between Galician and Cantabria is what I'm looking for.