I usually find the water in Spain lovely at this time of year. Its certainly a welcome relief from the hot sun. During the summer is the water is at its warmest when the average temperature is 64ºF (18ºC). In January the weather can really vary so obviously the water is going to be a lot cooler too. Aparently the best surfing spots are in Grenville and Lance Aux Epines Point.
If your there and not getting the greatest waves you could check out the link below from some other ideas of things to do
http://www.destination360.com/europe...ings-to-do.php