The little "gadget" on the left will keep you posted re the weather in the area. It won't take San Sebastian but if you click on the edit button and type in Bilbao it will give you the weather in that part of Spain. Maybe help you to decide whether clothing to take will be to cope with the cold or the rain........don't think the sun is going to be too much of a problem.....could be wrong of course! In San Sebastian the winter months from December to February see average temperatures of 9°C. Daytime highs are quite mild, around 12°C and average minimums at night reach 5°C to 6°C. Temperatures very rarely fall below 5°C and snow is highly unlikely. Rainfall is high. There are frequent showers and with the increasing strength of the wind huge storms can visit the area.