Past events suggest the phenomenon winds down after December and January. But will this year follow the pattern?
Image of the Day Heat Water
Conditions in May 2014 look similar to those in May 1997, a year that brought one of the most potent El Niño events of the 20th century.
Image of the Day Water
After appearing for two consecutive winters, La Niña appears to be taking some time off.
Cooler than normal conditions prevail in the central and eastern Pacific, but the event is so far considered weak.
Image of the Day Water Remote Sensing
The near-record water temperatures of 2015-16 has been followed by a modest, quiet appearance of La Niña.
Ocean conditions are not likely to help drought-stressed regions this spring. However, some broader changes might be coming in the Pacific.
Weakening trade winds are allowing warm water to move east across the Pacific in a telltale pattern.