There is no good or bad time to cross the BAY OF BISCAY. It is pot luck to be honest Take precautionary medication just in case you have a bad crossing.
My advice is to go on a fly cruise, only sail from Southampton when there is no other cruise available, for the destinations you want to visit.
I meant the Best Time Not "BEAST" Hope it not a Beast.
July, August, September but it can cut up rough at any time or be like a millpond even in the winter. It really is pot luck.....Sorry....Falan Dow.
We have sailed end of May.First time fine, second time force 9 out, return calm. Take medication in case.
Sailed through early October and returned mid-October. Both times weather was calm and the sea beautifully blue.