The Atlantic hurricane season starts June 1 and officially lasts until November 30. These dates delimit the period of each year when most tropical cyclones form in the Atlantic basin.
The Pacific hurricane season is an ongoing event in the annual cycle of tropical cyclone formation. It officially begins May 15 in the eastern Pacific, designated as the area east of 140ºW, and begins June 1 in the central Pacific, which is between the International Date Line and 140ºW. The season officially lasts until November 30.