Tropical Storm Peter was a short-lived tropical storm that formed after the end of the Atlantic hurricane season. It formed from an extratropical storm, and at first, it was a subtropical cyclone. However, as it moved over warmer waters, it began to gain strength. On December 9, 2003, it became a tropical cyclone. An eye formed within the cyclone, and Peter almost became a hurricane. It reached its peak winds of 70 mph (110 km/h), but wind shear and cooler waters quickly caused Peter to lose strength.