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Western Pacific Warm Pool: Why Do One-Third of the World's Typhoons Originate Here?

Key SummaryThe Western Pacific Warm Pool has the world's highest sea-surface temperatures, providing unlimited energy for typhoons. About 26 typhoons form here each year, making it a true typhoon factory.

What is the Western Pacific Warm Pool?

In the western Pacific, east of the Philippines and north of the equator, sea temperatures remain at 28–30°C, the highest in the world throughout the year. This area of warm water is known as the Western Pacific Warm Pool. It is like a pot of water that is always on the boil, serving as Earth's largest source of atmospheric energy.

Why has it become a "typhoon factory"?

On average, about 80 tropical cyclones form worldwide each year, and the northwestern Pacific accounts for about 26 of them—one-third of the total and the highest density in the world. The reason can be summed up in four words: favorable conditions—

  • Sea temperatures consistently meet the threshold: Typhoon formation requires sea temperatures above 26.5°C, which the warm pool meets throughout the year. As a result, the western Pacific is the only region where typhoons may occur in all 12 months of the year
  • A deep layer of warm water: The warm pool's warm water extends to a depth of hundreds of meters, so typhoons cannot stir up cold water and effectively "cut off their own food supply"
  • The monsoon trough provides initial disturbances: The summer monsoon trough continuously generates tropical disturbances, essentially serving as a "production line for typhoon embryos"
  • Sufficient Coriolis force: The main body of the warm pool lies between 5° and 20° north latitude, where Earth's rotation provides enough deflection for disturbances to start rotating

The warm pool's "temperament" determines the annual typhoon outlook

  • In years when the warm pool is warmer and larger, both the number and intensity of typhoons tend to be high
  • During El Niño, the warm pool expands eastward, and typhoon genesis locations shift eastward as well; during La Niña, the warm pool contracts and shifts westward, leading to more typhoons affecting nearshore areas
  • Research shows that the warm pool's area has continued to expand over recent decades amid global warming, providing a larger "playground" for stronger typhoons

A comparison with the Atlantic hurricane region

Sea temperatures in the main Atlantic hurricane-producing region show pronounced seasonality, and the region is essentially "closed for business" in winter and spring. The Western Pacific Warm Pool, by contrast, operates throughout the year. This is why typhoons occasionally form in January and February as well—for example, Typhoon 01 (PABUK) "started work" on January 1, 2019.

In one sentence

Once you understand the warm pool, you understand the typhoon's "family register": the secrets behind the world's greatest number of typhoons, their exceptional strength, and their year-round activity are all hidden in this pot of 30°C water.