Page 3 - Module
P. 3
El Niño and La Niña episodes typically last nine to 12 months, but some prolonged events may last
for years. While their frequency can be quite irregular, El Niño and La Niña events occur on average
every two to seven years. Typically, El Niño occurs more frequently than La Niña.
El Niño
El Niño means The Little Boy, or Christ Child in Spanish. El Niño was originally recognized by
fishermen off the coast of South America in the 1600s, with the appearance of unusually warm
water in the Pacific Ocean. The name was chosen based on the time of year (around December)
during which these warm waters events tended to occur.
The term El Niño refers to the large-scale ocean-atmosphere climate interaction linked to a periodic
warming in sea surface temperatures across the central and east-central Equatorial Pacific.
Typical El Niño effects are likely to develop over North America during the upcoming winter season.
Those include warmer-than-average temperatures over western and central Canada, and over the
western and northern United States. Wetter-than-average conditions are likely over portions of the
U.S. Gulf Coast and Florida, while drier-than-average conditions can be expected in the Ohio Valley
and the Pacific Northwest. The presence of El Niño can significantly influence weather patterns,
ocean conditions, and marine fisheries across large portions of the globe for an extended period of
time.
La Niña
La Niña means The Little Girl in Spanish. La Niña is also sometimes called El Viejo, anti-El Niño, or
simply "a cold event."
La Niña episodes represent periods of below-average sea surface temperatures across the east-
central Equatorial Pacific. Global climate La Niña impacts tend to be opposite those of El Niño
impacts. In the tropics, ocean temperature variations in La Niña also tend to be opposite those of El
Niño.
During a La Niña year, winter temperatures are warmer than normal in the Southeast and cooler
than normal in the Northwest.
