How jet streams and US weather are affected by the El Niño-Southern Oscillation

Learn about various ocean-atmosphere cycles impacting global weather patterns

Although the El Niño-Southern Oscillation is among the most impactful, the North Atlantic Oscillation strongly influences weather patterns in the Northeast US by periodically changing atmospheric pressure over the Atlantic. The North Pacific Oscillation fluctuates atmospheric pressure and sea-surface temperatures that affect winter temperatures over much of the US.

While El Niño moves warm Pacific Ocean waters east along the equator, La Niña moves them west, shifting where rainfall will become more common for months.

Mapping how the El Niño-Southern Oscillation affects weather patterns around the world

In the warm episode (El Niño), summers in India, Indonesia, Australia, and the Caribbean are drier than normal, while winters bring wetter, cooler conditions to the US Gulf Coast and warmer conditions to the Pacific Northwest. During the cold episode (La Niña), these are reversed, with India, Indonesia, and the southern Caribbean experiencing greater rainfall in the summers.

While El Niño moves warm Pacific Ocean waters east along the equator, La Niña moves them west, shifting where rainfall will become more common for months.

El Niño and La Niña are Pacific Ocean climate patterns that affect global weather

El Niño causes warm water to move east, disrupting ocean life and bringing wetter conditions to the southern US and drier ones to the North. La Niña strengthens the usual wind patterns, triggering cooler northern winters and more storms in the Pacific Northwest.

Breaking down the health effects of the El Niño-Southern Oscillation

Second only to the seasons, ENSO is the most significant source of variability in global climate, shifting rainfall and temperature patterns, particularly in Africa, Latin America, and South and Southeast Asia. The incidence of vector-borne diseases like malaria, respiratory diseases related to wildfire smoke, food insecurity, and drought-related health and nutritional impacts has been observed to be affected by ENSO.

How El Niño and La Niña affect the Pacific and Atlantic hurricane seasons

During El Niño, trade winds push warm waters across the Pacific toward northwest South America, affecting atmospheric circulation. The resulting strengthening of vertical wind speed and direction in the Atlantic basin disrupts hurricane formation, while the weakening of this wind shear in the central and eastern Pacific basins increases hurricane likelihood. El Niña, conversely, has the opposite impacts.

Understanding how the El Niño-Southern Oscillation is affected by climate change

An analysis of El Niño and La Niña patterns from 1901 to 2020 suggests that anthropogenic warming—global warming caused by humans—has at least partly contributed to increased ENSO variability in recent decades. While ENSO increases the likelihood of droughts and flooding across different regions, researchers say these severe weather events are made more extreme by greenhouse gas emissions.

Comparing La Niña and El Niño atmosphere-ocean feedback patterns

During La Niña, trade winds reinforce the flow of warm ocean water from the eastern to the western Pacific, allowing colder subsurface water in the eastern Pacific to rise to the surface. These changes reinforce overhead air movements by altering the air temperature near the ocean surface. During El Niño, these trade winds weaken or reverse, preventing upwelling by shifting warm water back to the eastern Pacific and displacing atmospheric circulation patterns.

Compare various El Niño-Southern Oscillations using maps of atmospheric and ocean variables

Because the intensity of the phases in the cycle is sensitive to small variations in atmospheric and ocean conditions and depends on complex interactions between these two systems, no two El Niño or La Niña events are identical. This contributes to the variability in the length of each phase, which is why an ENSO can last as little as two years or as long as seven.

How scientists use data to anticipate the phases of the El Niño-Southern Oscillation

Sea-surface temperatures across various regions of the equatorial Pacific Ocean can be compared with ocean temperatures elsewhere in the tropics to identify anomalies that indicate where in the ENSO cycle Earth finds itself. The "Niño 3.4" region in particular—known as the Ocean Niño Index—is a key indicator of ENSO phase and intensity.

Watch a visualization of how Earth's oceans impact its atmosphere, weather, and climate

Data from NASA satellites help view and explain global climate and weather patterns, such as El Niño and La Niña.

How jet streams, which reside in the troposphere, shape and confine pockets of atmospheric air

These fast-flowing ribbons of air are hundreds of kilometers wide and typically travel from west to east due to Earth's rotation, with the polar front and subtropical jets serving as major drivers of global circulation. Warmer air near the equator pushes the polar front jets toward the poles, which can buckle and deform them as they contain frigid polar vortex systems.

The global impacts of the 1877 'super' El Niño and what could result from similar future events

The 1877 El Niño event lasted approximately 18 months, raised temperatures in the Niño 3.4 region of the equatorial Pacific Ocean by 2.7 degrees Celsius (4.86 degrees Fahrenheit) above average, and contributed to a global famine that killed more than 50 million people. Such events are expected to exacerbate drought-related risks to global food security, driving up food prices worldwide. (Some readers may experience a paywall.)

Trade winds blow from east to west due to the Coriolis Effect

Warm air rises near the equator while cooler air sinks near the poles, creating circulation patterns that curve due to Earth's rotation. At the equator, doldrums—calm regions of no wind—build warm, moist air, creating storms.

How salt, sunlight, and wind drive ocean currents

The Atlantic Meridional Overturning Circulation plays a critical role in regulating earth's climate, but is threatened by climate change. Explore the effects of temperature, density, and salinity on ocean currents in this 13-minute PBS video.

Why the ozone hole altered Southern Hemisphere jet streams and rainfall patterns

Ozone depletion over Antarctica shifted jet streams southward, drying Australia while increasing rainfall in Uruguay, Brazil, Paraguay, and Argentina. Around the turn of the millennium, these trends began to slow as the Montreal Protocol phased out ozone-depleting substances.

El Niño, Spanish for 'the boy,' was named after Jesus Christ because the phenomenon resembled the weather changes observed around Christmastime.

Hurricanes, which rely on air consistently spinning in the same direction, cannot cross the equator because air curves in opposite directions north and south of it.

View the most turbulent flight routes and airports around the world

Using data from NOAA and the UK Met Office, these maps identify South America as the geographic region with the highest average turbulence. The most turbulent flights in North America are all found in the western United States.

Atmospheric rivers are the largest freshwater transport mechanism on Earth

Serving as highways that carry the water vapor equivalent of up to 15 times the average flow of water at the mouth of the Mississippi River, atmospheric rivers are approximately 400 to 600 kilometers (250 to 375 miles) wide and provide 30-50% of the annual precipitation of the US West Coast.

Learn all about different types of extreme weather

Find out in more detail about different types of extreme weather, from flooding to thunderstorms, from tropical cyclones to sandstorms, and more (w/ helpful videos).

Favorable conditions for wildfires are becoming more frequent in the western US

A new study of the American West shows that climate change is driving more days that are hot, dry, and windy—the perfect conditions for deadly wildfires.

Chaos theory—informally known as the butterfly effect—is the reason why weather forecasts are presented with probabilities rather than certainties.

Interactions between solar storms and Earth's magnetic field create auroras

Solar storms on the Sun's surface produce clouds of electrically charged particles, some of which make their way to Earth. Those trapped in Earth's magnetic field accelerate toward the north and south poles, colliding with atmospheric atoms and molecules in the process, which produces light.

Hurricane conditions are created in a University of Miami wind-wave tank

The SUrge-STructure-Atmosphere INteraction Wind Wave Laboratory contains a 38,000-gallon wave pool connected to a wind tunnel that can generate air currents of up to 155 mph. SUSTAIN allows scientists to study how the atmosphere interacts with the ocean in extreme weather.

Visualizing the year in US tornadoes, 2024

Between January and November 2024, over 1,700 tornadoes were documented to have touched down in the US, a relatively high number (and similar to the numbers in 2004, 2008, and 2011). This map shows their location across the country to help capture the number.

Chaos theory—informally known as the butterfly effect—is the reason why weather forecasts are presented with probabilities rather than certainties.

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

The difference between solstice and equinox, explained

A solstice marks the extremes in the amount of day or night, while the equinoxes come on days with a balance between the two. Learn why with this brief video.

Dirty lightning is a thunderstorm created from friction between rising and falling flows of ash and smoke during volcanic eruptions.

Ebola infects and disables immune cells, triggering a cascade of events that leads to small blood clots throughout the body, weakening blood vessels and interrupting blood flow to key organs.

The boiling temperature of water decreases with increasing elevation because the molecules need less energy to overcome the lower atmospheric pressure associated with thinner air.

Stars appear to twinkle because turbulence in the motion of molecules in Earth's atmosphere causes light to bend and wiggle rapidly on its way to the surface—a phenomenon called scintillation.

View the ten deadliest tornadoes in US history.

The US dollar is the most widely circulated currency in the world, and is involved in nearly 90% of global transactions

See the 25 of the best photos of auroras from around the world.

Visualize the path of every solar eclipse from 1900 to 2099 and see what each looks like when observed from different locations on Earth.

Some renewable energy sources may weaken the resiliency of electric grids by removing outage buffers provided by coal- and natural gas-fired plants, which provide the system with more time to find a new power source if a plant goes down.

Pure water does not conduct electricity because this flow of energy requires the movement of charged particles, and water is a neutral molecule.

Waves off the coast of Nazaré, Portugal, can reach over 100 feet and are caused by the area's deep underwater canyon geography

The Great Salt Lake's distinct dual coloration results from high-salinity organisms that only live in the northern portion and produce a purple protein.

Poison ivy will likely become both larger and more resilient due to climate change.

The American Society of Civil Engineers' infrastructure report card gave the US a C in 2025, its highest grade since the project launched in 1998.

Studies suggest when you sleep is as important as how much you get, and syncing with your circadian rhythms may lead to less fatigue and improved long-term health outcomes

Experimental hantavirus vaccines and therapies, still under development, have long been funded by the US military.

'Shogun,' a 1980s TV series, helped popularize sushi in the US by stimulating an American interest in Japanese culture.

Hear about the 250-year history of the United States Postal Service, complete with some of its strangest deliveries, important innovations, and the figures that made it an American institution.

The word 'jazz' evolved from 'jasm,' 19th-century American slang for 'energy'

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