The Pirate Hat is a new hat. When equipping this hat, the player will travel faster when using the boat, and also warms you as much as earmuffs. It is the only item that is warm both in water and on land. Despite being warm, it does not reduce the damage of blizzards.
The Pirate Hat warms you just about the same as of a Earmuffs.
The Pirate hat was added in the "Faster!" update.