El Niño forms every 2 to 10 years. The weather shifts wildly throughout the southern Pacific Ocean. Since it occured around Christmas, people started to call it El Niño. El Niño is another name for the Christ Child. Scientists around the world cannot fully explain the subtle interactions between the ocean and the atmosphere that produces El Niño. But they do know that this process involves weakening the southeastern trade winds that normally dictate the areas' weather and corresponding redistribution of warm weather throughout the Pacific Ocean. This is how it works. It starts with the warm surface temperature. This increases the convection. Then it weakens the trade winds. Finally this affects the eastward currents. All these things keep going on this route over and over again. This produces El Niño. That is how an El Niño is formed.