ENSO PAGE, provided by the National Weather Service in the San Francisco Bay Area, is a collection of links dealing with a variety of ENSO (El Nino/Southern Oscillation) related topics such as impacts, sea surface temperature charts, indices and analyses, and background information.

According to the National Oceanic and Atmospheric Adminstration (NOAA), El Nino is "a disruption of the ocean-atmosphere system in the tropical Pacific having important consequences for weather around the globe." It is caused by a change in trade wind patterns in the central and western Pacific ocean, and causes a large volume of ocean to be warmed (typically about 20 degrees of latitude by 90 degrees of longitude). It happens at irregular intervals and has global climatic consequences (regional flooding and droughts, in particular).