I make 3 Biscay crossings in winter, mostly for charter
companys , and in one with a L380 club , all i can say is forget to sail the close to the coast to spain
unles you are a masochist, almost all the harbours in the north tip of spain
are dead traps in severe gales or storms, and you are moving under the continental shelf , one fool dude sail a brand new Bene for moorings from Sables DÒlone to la coruña and make a straight course across Biscay , get caught in a sever gale a day ahead of spain and made Santander surfing big waves , he got stuck there for almost 15 days , the cap got presed by Moorings to make progres and leave harbour with a horrible sea condition outside, he broke the mainsail
, and the boom... i know that because i leave Olone behind the gale and reach la coruña before and later meet the cap in la coruña, lucky guy you know?
For the Op , i sugest to sail south and leave the area as soon as posible until North coast of Spain, from there is almost a piece of cake, well you got Finisterre and later the coast of Portugal
, with a nice window you will be ok, there is no real weather windows in Biscay in winter , if the met say 2 days , expect one .... and keep a good distance from the shelf, in doubt or with problems head
west or pull the pedal to the metal, Biscay is really rough in bad weather, hope you enjoy your crossing ....