A sou'wester is a waterproof hat that is worn especially by sailors in stormy weather. It has a wide brim at the back to keep your neck dry. a hat made of shiny material that keeps the rain off, with a wide piece at the back that covers your neck (southwester)
of wind; from the west lying in or toward the west from the west; "the wind blew westerly" toward the west; "we began to steer away westerly"- Daniel Defoe