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

SPherical map of tropical Pacific showing the August 2021 temperature anomaly


The central tropical Pacific Ocean is in a neutral climate state, but the odds of at least a weak La Niña emerging this fall have risen to 70-80 percent.

Latest official ENSO update

Latest ENSO blog update

(image at left) Map of August 2021 sea surface temperatures compared to average, showing cooler-than-average conditions (blue) across most of the tropical Pacific basin. NOAA Climate.gov image, based on NOAA EVL data.

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 and La Niña—together called "ENSO," which is short for El Niño-Southern Oscillation—are anchored in the tropical Pacific, but they affect climate "downstream" in the United States. In the summer, ENSO's primary influence on U.S. climate is on the hurricane season in both the eastern Pacific and the Atlantic. In winter, they influence 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

Graph of ONI index since 1950

ENSO and Climate Change: What does the new IPCC report say?

September 23, 2021

The latest IPCC report on the Physical Science Basis of climate change covers pretty much everything you can think of, including ENSO. So what were its conclusions? Our ENSO Bloggers walk us through the report's conclusions and what they mean. Read more.

The monthly Oceanic Niño Index since 1950. The latest IPCC report concludes that recent changes in the behavior of ENSO—including more high-amplitude events—are within the range of past natural variability.