El Niño & La Niña (El Niño-Southern Oscillation)
Compared to last month, models have slightly backed off their confidence—from 75% to 55-60%—that La Niña will occur this fall and winter. While tropical Pacific waters have cooled (see map at left), the trade winds have not showed the La-Niña-like strengthening needed to amplify cold-water upwelling. The current outlook favors a weak event, but remember: impacts aren't always tied to event strength.
El Niño and La Niña are the warm and cool phases of a recurring climate pattern across the tropical Pacific—the El Niño-Southern Oscillation, or “ENSO” for short.
The pattern can shift back and forth irregularly every two to seven years, and each phase triggers predictable disruptions of temperature, precipitation, and winds.
These changes disrupt the large-scale air movements in the tropics, triggering a cascade of global side effects.
NOAA declared El Niño oficially over at the end of May 2016. Meanwhile, conditions are favorable for La Niña to emerge within 6 months. Neither phase of ENSO has a strong influence on summer temperature or precipitation in the U.S. However, if La Niña develops by late summer or fall, it may suppress hurricane activity in the central and eastern Pacific basins and enhance it in the Atlantic.
El Niño and La Niña have their strongest impact on global climate during the Northern Hemisphere winter & early spring. However, parts of the tropics and Southern Hemisphere sub-tropics feel the effects of ENSO during Northern Hemisphere summer months (June-August).
The map at left shows typical rainfall and temperature patterns in the Northern Hemisphere summer during La Niña events. These patterns become more likely during La Niña events, but they are not guaranteed. NOAA Climate.gov map.
Featured Resources & Articles
Images & Maps
ENSO across NOAA
Societal & ecosystem impacts
Regional & Local Impacts
ENSO @ the Ocean Institute of Peru (Spanish)
ENSO @ the Centro Internacional para la Investigación del Fenómeno de El Niño (CIIFEN) (western South America, Spanish)
Events & Announcements
NOAA National Weather Service Daily Briefing
Briefing page with forecasts, discussions, maps, assessments, and severe weather outlooks for today’s developing weather patterns across the United States.
El Nino: What's Next?
February 18, 11 am CT
Hosted by SCIPP
NOAA Monthly Climate Briefing for Media
Thursday, February 18, at 11 am EST
Teleconference for public media on past month’s weather & climate conditions for the U.S. & globe, an update on El Niño, and NOAA’s 3-month climate outlook.
California Winter Status Update
January 26, 4 - 6 pm EST