This classic rain hat is also known as sou'wester. The sou'wester is a seafarer's waterproof headgear. Its special feature is the wide brim, which is longer in the back to keep the neck warm and dry by preventing rainwater from entering the clothes.
Now where does this hat derive its name from? Most rain falls in a south-westerly direction, which is why the hat is named after the south-west point of the compass. It is possible that the name of this hat has its origins in Norway, as does its creation.