There is an increase in rainfall in this region due to the evaporation of the warmer water. Air pressure in the western Pacific near Australia is normally low. Air pressure in the eastern Pacific near South America is normally high. Winds normally blow from the high pressure area, South America, towards the low pressure area, Australia. These normal winds are called the trade winds.
Winds blow surface water.
Surface water is warmer than deeper water. Usually, warm water is blown by the trade winds from the coast of South America towards the coast of Australia. The accumulation of warm water found in the western Pacific near Australia as a result is called the warm pool. This slows down or reverses the trade winds. Warm water is not blown away from the coast of South America.