El Niño has officially arrived and it could bring unprecedented weather

Brace yourselves

According to the US National Oceanic and Atmospheric Administration (NOAA), El Niño conditions are now under way in the tropical Pacific.

This comes as sea surface temperatures having risen sharply in recent months.

As per many forecasts, this could end up as a so-called “super” El Niño, and even be among the strongest ever recorded.

The new El Niño bring another record-hot year, most likely next year, with disruption to weather, food supplies and economies running well into that year.

It comes on top of decades of human-caused warming.

The latest announcement by NOAA is not a surprise, as forecasters have expected this warming phase, after the cooler “sister” pattern, La Niña, ended earlier this year.

In the central and tropical Pacific, sea surface temperatures have now passed the 0.5C-above-average threshold that US scientists use to define an El Niño event.

How the El Niño conditions developed

The agency said that “El Niño conditions developed over the past month, as shown by above-average sea surface temperatures (SSTs) across the central to eastern equatorial Pacific Ocean”.

As a sign that the atmosphere is now responding to the warmer ocean, not just the ocean warming on its own, NOAA has also seen the winds above the equatorial Pacific begin to shift.

The intensity of El Niño is measured by how far sea surface temperatures rise above average in a key zone of the Pacific.

And a strong event of this is defined as more than 1.5C above average; a very strong one above 2C.

NOAA’s June outlook says that: “there is a 63% chance of a very strong El Niño during November-January, that would rank among the largest El Niño events in the historical record going back to 1950”.

Since then, the three strongest events have been in 1982/83, 1997/98 and 2015/16.

As some of the latest US and European (ECMWF) models go further, they show temperatures in the tropical Pacific potentially climbing more than 3C above average by the end of the year.

However, the US agency urged some caution on what their strength prediction implies.

“Even very strong El Niño events do not lead to the expected impact everywhere, but stronger events can more significantly tilt the odds in favour of expected outcomes.”

The warmer planet and the biggest concerns

The biggest concern about what El Niño is and why could it mean record temperatures is that all this is happening on an already much hotter planet.

According to Prof Adam Scaife, head of monthly to decadal prediction at the UK Met Office, “we do need to worry about the impacts”.

“The current El Niño is… riding on top of a substantial amount of global warming.”

“This means that the actual temperatures in affected regions could well be unprecedented, as the warming from El Niño is being topped up by climate change.”

Typically, a very strong El Niño lifts global air temperatures by around 0.2C, releasing heat stored in the ocean into the atmosphere.

And to top it off, that extra blast now lands on a world that is already setting records.

The warmest year on record, which was 2024, was boosted by an El Niño that was not even especially strong.

The following year, 2025, still came in as the third warmest year on record, hotter even than the super El Niño year of 2016, despite the cooling drag of a La Niña event.

Prof Scaife said that “at the end of this year and into 2027, we're likely to see very high temperatures globally”.

“In 2027, we're likely to see excess heat on top of the global warming we've already got, and that could easily lead to another year above 1.5 degrees [of warming above late-19th-Century levels].”

Lis Stephens, professor of climate risk and resilience at the University of Reading, said that “while that sounds like a good thing, for Central America that leads to a lot less rainfall and potentially drought conditions”.

Even if faintly, the UK also feels El Niño.

It can tilt the odds towards a mild start and cold end to winter, though the links are loose.