Super El Niño has developed an extra arm, an ominous map reveals – indicating that the patch of warm water in the Pacific Ocean has significantly expanded.
Pictures shared by Senamhi, Peru's national meteorological and hydrological service, reveal a second 'limb' of heat has developed in the last few weeks.
An image, shared on September 30, shows a band of warm water stretching out from the coast off Ecuador and Peru.
But another image, created from data collected two weeks later on October 14, shows the heat has spread down along the coast of Chile and out into the south–east Pacific, creating what appears to be a second arm branching from the main pool of warm water.
The expansion means a much larger swathe of the eastern Pacific is now experiencing above–average sea–surface temperatures, with some areas more than 3°C (5.4°F) warmer than normal.
And it adds further weight to warnings that the climate phenomenon is building up into the strongest event in a millennium.
'I think that this year's El Niño event is likely to be the strongest in 1,000 years if the latest models of its peak prove accurate,' climate scientist Zeke Hausfather said.
This picture, created from data collected on October 14, shows the heat has spread down along the coast of Chile and out into the south–east Pacific, creating what appears to be a second arm branching from the main pool of warm water
It represents an obvious development from this image, from September 30, which just shows one band of warm water
Recent updates indicate El Niño will continue to strengthen ahead of a forecasted peak in December.
Scientists say the powerful climate pattern is likely to influence temperatures and rainfall across much of the world in the coming months.
Britons have already been warned to expect a wet and stormy autumn followed by a cold and calm winter, as ministers urge people to stock up on food to prepare for extreme weather.
Last month, the Department for Environment, Food and Rural Affairs said: 'If you've got a store of a bit of food that can keep you going for a while before the emergency services can get to you, you're going to be a lot better off than if you haven't.'
Dr Chloe Brimicombe, a climate researcher at the University of Oxford, said colder, calmer weather can also create challenges for Britain's renewable energy supply.
'Wind power generates 40 per cent or more of the UK's electricity during winter and cold, calm periods can require more gas power to make up for lower wind generation and increased demand for heating,' she wrote on The Conversation.
Meteorologists recently released striking maps showing vast swathes of the planet shaded red, signalling an increased chance of hotter–than–average temperatures
Forecasters expect Super El Niño to peak in December and remain strong into the spring of next year
The latest warning comes shortly after meteorologists shared striking maps showing large areas of the globe shaded red, indicating a heightened likelihood of above–average temperatures.
According to the World Meteorological Organisation, there is a near–100 per cent chance that El Niño will persist through February next year.
US meteorologist Ryan Maue described the outlook in a post on X, writing: 'New maps show Earth almost entirely in the red.
'El Niño continues at "maximum power" into the winter with planetary heating dialled up everywhere except the United States.'
The update also points to an overwhelming likelihood of above–average sea surface temperatures across large parts of the globe during the final months of 2026.
Scientists warn that the combination of a powerful El Niño and exceptionally warm oceans could increase the risk of heat extremes, floods and droughts in different regions of the world for months to come.
El Niño is part of a naturally occurring weather cycle called the El Niño Southern Oscillation that changes between a hot and cool phase once every two to seven years.
During the hot, El Niño part of the cycle, the trade winds that normally blow warm water from the Pacific towards Australia slow or even reverse.
This allows warm water to collect near the surface of the equatorial Pacific Ocean off the west coast of South America, driving up global average temperatures.
Scientists have warned that this year's 'Super El Niño' has already smashed historical temperature records, months before reaching its peak.
'A strong El Niño is likely to increase the chances of wetter, stormier conditions for the UK from October to December,' said Dr Amulya Chevuturi, senior hydroclimate scientist, UK Centre for Ecology & Hydrology.
'The North West is expected to be worse affected than the South East.'