December is where northern Spain wins an argument nobody expects it to. Zarautz in December is clean fifteen days out of thirty, which is ahead of the famous points of Portugal and Morocco in the same month: half of midwinter surfable, on two and a half kilometres of sand with a town living right behind it.
The reason is the same geometry as the rest of the year. The coast faces north-north-west, so the Atlantic storms arrive at an angle rather than head-on, and the southerly that comes off the land holds the mornings open while open west-facing coasts are being flattened by the same weather.
The cost is daylight and temperature. There are around nine hours of light, the water is at 14°C, and the swell is big enough often enough that the day gets chosen for you.
