What Is El Niño? Current Climate News
El Niño is one of those terms that most people have heard, but relatively few people could confidently explain. It appears regularly in weather forecasts and news reports, often linked to heatwaves, droughts, floods, and record-breaking temperatures. But El Niño is not a storm, a hurricane, or a weather event in its own right.
Instead, it is a natural climate pattern that develops in the Pacific Ocean, and understanding it starts with understanding what normally happens there.
What Normally Happens?
Across the tropical Pacific, trade winds usually blow from east to west. As they move across the ocean, they push warm surface water towards Southeast Asia and Australia, where warm water piles up in the western Pacific.
Along the west coast of South America, deeper water rises to replace it. This process, known as upwelling, brings nutrients to the surface and supports some of the most productive marine ecosystems on Earth. Under these normal conditions, the western Pacific tends to be warmer and wetter, while the eastern Pacific remains cooler because of the continual supply of deeper water.
Along the west coast of South America, deeper water rises to replace it. This process, known as upwelling, brings nutrients to the surface and supports some of the most productive marine ecosystems on Earth. Under these normal conditions, the western Pacific tends to be warmer and wetter, while the eastern Pacific remains cooler because of the continual supply of deeper water.
When El Niño Develops
During an El Niño event, the trade winds weaken. Without those winds pushing warm water westward, warm surface water spreads back across the central and eastern Pacific. As this happens, upwelling along the South American coastline is reduced.
With fewer nutrients reaching the surface, productivity declines. Phytoplankton growth can decrease, affecting the food supply available to fish and other marine life.
At the same time, the distribution of heat across the Pacific changes. Areas that are normally cooler become unusually warm, altering patterns of rainfall and atmospheric circulation.
Why Does It Affect Weather?
The Pacific covers around a third of Earth's surface, so changes in its temperature can influence the atmosphere above it.
Warm ocean water increases evaporation, which can affect cloud formation and precipitation. When the pattern of warm water shifts during El Niño, the location of major rainfall systems can shift too.
This is why El Niño can influence weather far beyond the Pacific Ocean itself.
Depending on the event, some regions may experience unusually dry conditions, while others receive more rainfall than normal. Global average temperatures also tend to be higher during El Niño years because additional heat is transferred from the ocean into the atmosphere. Not every heatwave, flood, or drought can be linked directly to El Niño, but it can increase the likelihood of certain weather patterns developing.
What About Marine Life?
Reduced upwelling means fewer nutrients reach surface waters, which can affect the growth of phytoplankton. Because these microscopic organisms form the base of many marine food webs, changes at this level can affect fish populations, seabirds, and marine mammals further up the chain.
For regions that depend heavily on nutrient-rich waters, El Niño can have significant ecological and economic consequences.
What About La Niña?
El Niño is only one phase of a larger cycle known as the El Niño-Southern Oscillation (ENSO).
The opposite phase is called La Niña.
During La Niña, trade winds strengthen, pushing even more warm water towards the western Pacific and increasing upwelling in the east. Sea surface temperatures in parts of the eastern Pacific become cooler than average, often producing weather patterns that differ from those seen during El Niño.
Why Is El Niño in the News Right Now?
The World Meteorological Organisation reports that El Niño is firmly established and is expected to strengthen further. Current forecasts suggest there is a near 100% likelihood that it will persist into February 2027, with exceptionally warm conditions across the tropical Pacific supporting further intensification.
This has attracted significant attention because strong El Niño events have the potential to shift rainfall and temperature patterns around the world. Some regions could experience increased flood risk, while others may face drought, heatwaves, or other forms of extreme weather.
Forecasts cannot tell us exactly what conditions will occur in a specific location. Instead, they indicate that the large-scale climate patterns associated with El Niño are becoming more pronounced. As a result, meteorological organisations and national weather services are increasing preparedness efforts and strengthening early-warning systems in anticipation of a potentially significant event.