A Pacific typhoon or tropical storm is a tropical cyclone that develops in the northwestern part of the Pacific Ocean between 180° and 100°E. For organizational purposes, the northern Pacific Ocean is divided into three regions: the eastern (North America to 140°W), central (140°W to 180°), and western (180° to 100°E). A Pacific typhoon, then, is a tropical cyclone in the northern Pacific Ocean west of 180°. Identical phenomena in the eastern north Pacific are called hurricanes, with tropical cyclones moving into the Western Pacific re-designated as typhoons.
Within the Northwestern Pacific there are no official typhoon seasons as tropical cyclones form throughout the year. The majority of storms form between May and December whilst tropical cyclone formation is at a minimum between January and April. The Northwestern Pacific features some of the most intense tropical cyclones on record.