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

Spherical map of tropical Pacific SSTs in December 2020


La Niña—the cool phase of the El Niño-Southern Oscillation climate pattern—was firmly in place across the tropical Pacific in December 2020. Forecasters estimate a 95% chance La Niña will last through Northern Hemisphere winter. La Niña can influence seasonal climate in the United States. Conditions so far have not looked especially La Niña-like, but winter is far from over.

Latest official ENSO update

Latest ENSO blog update

(image at left) Maps of December 2020 sea surface temperatures compared to average show a large swath of cooler than average waters in the tropical Pacific, one of the signs 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 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. In winter, it influences the jet stream and the path of storms that move from the Pacific over the United States. 

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

Map of SST anomalies in December 2020, cropped to the tropical Pacific

January 2021 La Niña update: remote destinations

January 14, 2021

The tropical Pacific seems so far away, yet it affects weather and climate around the world. Our blogger updates you on the current La Niña event and what forecasters think is next. Read more

(left) Surrounded by warmer-than-average waters to the north and south, a wide swath of cooler-than-average surface waters across the tropical Pacific Ocean in December 2020 was one sign that La Niña was underway. NOAA Climate.gov image from Data Snapshots.