Why the familiar-sounding warning of a potential super El Niño sounds shriller this time

The latest advisory issued by the Climate Prediction Center of US’s National Oceanic and Atmospheric Administration (NOAA) earlier this month warns of a super El Niño, with an 82 per cent chance in the May–July period. The Climate Prediction Centre further predicts that the event may peak during the northern hemisphere winter, between November 2026 and January 2027, and linger into early 2027.

That alone would be enough to attract headlines.

But some climatologists are going further. Along with the US’s Climate Prediction Centre, the European Centre for Medium-Range Weather Forecasts (ECMWF ), World Meteorological Organization (WMO) and IRI (International Research Institute for Climate and Society), among others, suggest this warming could become exceptionally intense, perhaps even turning into what is loosely called a "super El Niño".

This makes people nervous for good reason. Strong El Niño episodes are associated with drought, crop stress, and disruptions in rainfall patterns worldwide. They also trigger heatwaves and increase wildfire risk, and are an environmental threat; warm oceans often bleach delicate corals.

For India, the worry is immediate: weak southwest monsoon rainfall, droughts across various parts of the country.

But before assuming disaster, it helps to understand what exactly El Niño is, what it is not, and why India's fate does not depend on this Pacific event alone.

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The name El Niño itself originates from fisher people. Spanish-speaking fishermen off the coast of Peru noticed that in some years the coastal waters turned unusually warm, affecting the fish catch. El Niño usually reduces anchoveta catch, a high-value fish that prefers cold, nutrient-rich seawater. But warmer ocean waters during El Niño favour other species. So fishermen could catch more mahi-mahi, tuna, bonito, and shrimp during these years. They called it El Niño, meaning "the boy child", a reference to the child Christ. Quite obviously, they call its counterpart, La Niña, “the girl child” – years in which the waters were unusually cold.

These are not annual events. They typically appear every two to seven years.

But what is this event?

Imagine the vast Pacific Ocean between South America on one side and Indonesia and Australia on the other. Somewhere in that enormous equatorial stretch, the ocean and atmosphere engage in a periodic rearrangement. During El Niño, sea surface waters in the eastern and central Pacific become warmer than normal. During La Niña, they become cooler than normal.

That is the ocean part. But the atmosphere is also involved.

Meteorologists noticed long ago that air pressure across the Pacific behaves like a seesaw. When pressure falls in one region, it rises in another. This back-and-forth shifting was named the Southern Oscillation.

Later, scientists realised these were not separate phenomena at all.

Warm ocean water changes evaporation. Evaporation induces cloud formation. Cloud formation changes wind circulation. Winds, in turn, push ocean waters around. One feeds the other.

So the ocean warming called El Niño and the atmospheric pressure seesaw called Southern Oscillation were brought together into one term: ENSO (El Niño Southern Oscillation).

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Why should India care about a patch of ocean thousands of kilometres away?

Because the Earth's climate is an interconnected machine and the impacts are not small.

During El Niño years, rainfall tends to move eastward across the Pacific, so places near Peru and Ecuador can get wetter, while Indonesia and Australia can become drier.

India watches the phenomenon closely, as in many El Niño years, less moisture reaches the Indian subcontinent. Winds that normally help drive the Indian southwest monsoon, vital for farming, water storage (ground water and surface storage like dams), and hydroelectric generation, can weaken. Historically, many Indian drought years have coincided with El Niño.

But not always.

Not every El Niño is the same, which is where people often get confused. Some are weak, some are moderate, and some are much stronger. Few superstrong.

The 2018–19 El Niño was considered weak. The 2015–16 event was among the strongest ever recorded.

How do scientists measure this?

Think of how a doctor checks your temperature.

Your body's true internal temperature cannot be measured directly. Nonetheless, a thermometer under the arm or in the mouth gives a reliable indicator of what is happening inside.

Climate scientists do something similar.

They do not average the temperature of the entire Pacific Ocean. Instead, they monitor a particular patch called the Niño 3.4 region, a large stretch of equatorial Pacific roughly midway between Peru and Indonesia. The Niño 3.4 region is a kind of climate thermometer for the Pacific.

The key measurement is called the Ocean Niño Index (ONI). It tracks how much warmer or cooler the sea surface is compared to normal.

If the ONI rises above 0.5°C, El Niño conditions are considered established. Between 0.5°C and 1°C, it is weak. Between 1°C and 1.5°C, moderate. Higher values indicate stronger events.

How is ONI calculated?

Sea surface temperature, like everything on the planet, fluctuates on hourly, daily, weekly, and monthly timescales. Suppose monthly temperatures behave like this: January: 26.1°C; February: 26.8°C; March: 27.2°C; April: 26.5°C; May: 27.5°C and June: 28.0°C

If you stare at these month by month, the jumps look messy. Up, then down, then sharply up again. Hard to see the trend.

So climatologists use something called a rolling average. Take January, February, and March. Average them. That gives 26.7°C. Now shift the window forward by one month. February, March, April. Average them. That gives 26.8°C. Then March-April-May: 27.1°C. Then April-May-June: 27.3°C.

Now the pattern becomes clearer. The warming is steadily building.

That is why climate scientists use rolling averages for El Niño rather than a single hot month or one unusually cool week.

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So where do things stand now?

Despite the alarming forecasts, El Niño has not officially been declared as of May 2026.

This fine print matters.

Actual ONI values are still below the event threshold.

The rolling average of sea surface temperature for January–March 2026 was around –0.2°C to –0.3°C, and for February–April 2026, around 0.0°C. The ONI for March–May 2026 is estimated around +0.1°C to +0.3°C. Nonetheless, the latest weekly value monitored by NOAA around May 13, 2026, had surged to +0.9°C.

In other words, the warming is real and speeding up. That is an upward trend, yes. But not yet El Niño territory. So what exists right now is a warning, not a panic.

And even if El Niño does arrive, India's monsoon story is not written solely by the Pacific phenomenon.

Meteorologists learned this the hard way in 1997. That year saw one of the strongest El Niño events ever recorded. Expectations were grim. A severe Indian monsoon failure seemed likely.

But something odd happened. India's monsoon did not collapse as badly as expected. This became a scientific puzzle.

What had protected the monsoon? The answer lay not in the Pacific, but closer home.

In 1999, researchers NH Saji, BN Goswami, PN Vinayachandran, and Toshio Yamagata, writing in the Nature journal, formally described another climate phenomenon: the Indian Ocean Dipole, or IOD.

The Indian Ocean, they showed, has its own east-west climate oscillation like a giant oceanic east–west seesaw.

The IOD itself is fairly easy to understand. Think of the Indian Ocean as a long basin that can tilt in temperature. In a positive IOD, the western Indian Ocean near East Africa is warmer than normal. At the same time, the eastern side near Indonesia is cooler than normal. In a negative IOD, the pattern flips.

Why does this matter? Because warm water heats the air above it. Warm air rises, helping form clouds and rain. So, a positive IOD often helps draw moisture and convection towards the Indian side of the ocean basin and can support Indian monsoon rainfall. A negative IOD can do the reverse.

Then came follow-up research in the early 2000s by Karumuri Ashok, Guan, Yamagata, and others, including Indian scientists like BN Goswami. They helped solve the 1997 mystery. They showed that a positive IOD had likely compensated for some of El Niño’s damaging influence during 1997. In simple terms, El Niño may pull the Indian monsoon down, but a positive IOD can push it back up.

That changed forecasting. Before that, the story often sounded simple; El Niño means weak Indian monsoon.

Since this finding, the association has become more nuanced. El Niño alone may weaken rainfall. El Niño plus positive IOD may soften the blow.

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A tug of war. The Pacific is pulling one way. The Indian Ocean is pushing back.

The IOD usually develops during the middle of the year, strengthens around September to November, then fades. So naturally, forecasters are now watching it closely this time too.

What does the recent outlook say? The Australian Bureau of Meteorology (the leading agency monitoring the IOD) says the IOD was neutral in early May 2026, with an index of -0.04°C, and that a positive event is possible later in winter–spring. However, the timing and strength remain uncertain.

That means the Pacific appears to be warming up towards El Niño. At the same time, the Indian Ocean may later tilt towards a positive IOD. If El Niño strengthens, it may try to weaken the monsoon. If a positive IOD develops, it may provide some counterforce. That sounds encouraging for India.

In 1997, IOD had the upper hand; despite a severe El Niño, the Indian monsoon was near normal.

But which side will the scales tilt in 2027? Too early to say.

Caution is necessary, however. IOD forecasts made far in advance are less reliable than those made in the short term. Ocean-atmosphere systems can shift unexpectedly in the Indian Ocean.

For now, the warning lights are on. That is not the same as the storm having arrived.