Although tropical cyclones can occur in many parts of the world, about 75% of all tropical cyclones form in the Northern Hemisphere. The western North Pacific Ocean has the greatest number of storms per year. There are also areas that are not affected by tropical cyclones, such as the South Atlantic where the ocean is too cool (see Figure 5).

The following is a listing of specific areas of the world which are affected by tropical cyclones:

• Tropical North Atlantic, Caribbean Sea, and Gulf of Mexico.
• Eastern North Pacific (from the west coast of Mexico to 180 degrees West)
• Western North Pacific (Philippine Islands and the South China Sea extending to 180 degrees East)
• Bay of Bengal
• Arabian Sea
• South Indian Ocean (off the coast of Madagascar extending eastward to the central Indian Ocean)
• Northwest coast of Australia extending westward to the central Indian Ocean
• South Pacific Ocean from eastern Australia to about 140 degrees West.