I swung through Seaham this afternoon on my way back to the office from a job, was about half tide up and the swells were pretty big at that point, loads of white water coming over the north pier nad the south pier was just about under water as the swells rolled along it. That said it's not a "rough" sea as such, more big ground swells.
Good luck to anyone venturing out but be careful, this sort of sea will have plenty of bigger "rogue" waves thrown in which can easlily get you in trouble if they hit the beach unexpected in the dark...