El Niño is a climate phenomenon that influences sea surface temperatures and ocean currents.

During normal years, the trade winds blow strongly from east to west across the Pacific Ocean. This carries warm surface waters in the same direction, and brings thunderstorms and monsoon conditions to Indonesia and Australia. Meantime, in the eastern Pacific (off the coast of Peru and Ecuador), this movement of warm water allows for the upwelling of deep, cold ocean water.

During El Niño years, the opposite occurs because the trade winds weaken. Because the winds aren't moving the warm water to the west, the eastern Pacific Ocean begins to heat up. This causes upwelling to cease. As the ocean waters warm off the coast of South America, the ocean currents start shifting more warm water eastward. Increased storms and precipitation also move eastward. Therefore, El Niño years are associated with an increase in flooding in South America, which Indonesia experiences drought conditions. Because the ocean and atmosphere are closely connected, El Niño also influences the weather patterns in other areas of the world.