"The El Niño weather phenomenon occurs irregularly. Right now we have no accurate way to predict when an El Niño is about to occur. By studying historical records, we have learned that a new El Niño takes place every two to seven years.   

"While we don't have an accurate schedule when they will occur, there are signs that can tell us that an El Niño is coming. The best sign is unusually warm water temperatures along and on both sides of the equator in the Pacific Ocean.  

"To watch for temperature changes, meteorologists are using special satellites to watch the Pacific. They also have special ocean buoys in the Pacific that monitor water temperature and send in current information.  

NASA, in partnership with French scientists, is using these satellites not only to monitor the Pacific, but to monitor all of the Earth's oceans. To see their results, visit here.  

"The length of an El Niño depends on how long the trade winds are in a weakened condition. The longest El Niño occurred for five years during 1990 through 1995."