El Niño & La Niña (El Niño-Southern Oscillation)

El Niño Watch

Sea surface temperatures in the tropical Pacific were comfortably above the threshold for El Niño in October 2018, but the atmospheric response is lagging. A deep pool of warm water is available below the surface to renew and sustain the surface anomaly, however, and forecasters estimate an 80% chance of a weak El Niño during Northern Hemisphere winter 2018-19. 

More ENSO status information
Latest official ENSO update
Latest ENSO blog update

(image at left) Difference from average sea surface temperatures at the equator in the tropical Pacific. 

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.

More about El Niño
What is El Niño in a nutshell?
Understanding El Niño (video)
FAQs
ENSO alert system criteria
ENSO essentials
Educational Resources on ENSO

El Niño is anchored in the tropical Pacific, but it affects seasonal climate "downstream" in the United States. This map shows some of the precipitation and temperature impacts we may experience if El Niño develops this winter as predicted, but not all impacts occur during every event, and their strength and exact location can vary. 

Typical U.S La Niña impacts
Winter temperature and precipitation
Hurricane season impacts
Current outlooks
6-10 day outlook
8-14 day outlook
1-month outlook
3-month outlook

El Niño and La Niña have their strongest impact on global climate during the Northern Hemisphere winter.  The map at left shows some of the precipitation and temperature patterns that might occur this coming winter if El Niño develops as predicted. However, not all impacts appear during every El Niño event.  

More information
ENSO's cascade of global impacts
The Walker Circulation
More maps of global impacts of La Niña and El Niño

November 2018 ENSO Update: (Just a little bit of ) history repeating

November 9, 2018

The east-central equatorial Pacific is warmer than average, but El Niño hasn’t arrived quite yet. What’s the ENSO latest?

Read more

Both dynamical (solid purple) and statistical (dashed line) climate models predict that tropical Pacific temperatures in the Niño3.4 Index region will exceed the El Niño threshold.