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

spherical map of the Pacific centered on the equator showing surface temperatures compared to average in October 2020


La Niña—the cool phase of the El Niño-Southern Oscillation climate pattern—strengthened in the tropical Pacific in October 2020. Forecasters estimate a 95% chance La Niña will last through Northern Hemisphere winter, and they say the event is likely to be a relatively strong one. La Niña winters tend to favor warm and dry conditions in the southern tier of the U.S. and snowier-than-average conditions across much of the northern U.S. 

Latest official ENSO update

Latest ENSO blog update

(image at left) Cooler-than-average surface waters in the central and eastern tropical Pacific in October 2020 are one sign of La Niña. 

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)
ENSO alert system criteria
ENSO essentials
Educational Resources on ENSO

Globes showing typical climate impacts over the U.S. during El Niño and La Niñaca

El Niño is anchored in the tropical Pacific, but it affects seasonal climate "downstream" in the United States. In the summer, El Niño's primary influence on U.S. climate is on the hurricane season in both the eastern Pacific and the Atlantic. 

Typical ENSO 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 influence on global climate during the Northern Hemisphere winter. During La Niña winters, the southern tier of the United States is often drier than normal. Northern Australia, Indonesia, and the Philippines are often wetter than normal. 

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

small maps of US precipitation anomalies during past La Niña winters

What to expect this winter: November update to NOAA’s 2020-21 Winter Outlook

November 25, 2020

Will the current La Niña influence the weather over the U.S. this winter? The Climate Prediction Center’s Mike Halpert dishes out the details of the November update to NOAA’s 2020-21 winter outlook. Read more

(left) U.S. precipitation patterns during past La Niña winters. Visit the blog to see the 20 strongest events since 1950.