"nor'easter" is also the name for the special foul- weather gear
and on the the other side of the pond this is known as a "sou'wester". At least that is certainly a foul weather hat (like Paddington Bear wears - I had one as a child) and I think refers also to the rest of the gear. I wouldn't know if the gears are similar. Presumably if a sou'wester buttons down the front, a nor'easter buttons down the back?
Rod