An 'unprecedented' El Niño will trigger severe storms and power cuts that could leave millions offline this winter, experts have warned.

Around 26.7 million Britons lost broadband connection last year, according to new research from Uswitch - up almost a fifth on the previous year.

Power cuts are now the leading cause of internet outages, eclipsing provider faults and contributing to 41 per cent of service failures.

Now, with a Super El Niño forecast to bring wet and stormy conditions this autumn and winter, Uswitch is warning households to prepare for even more service blackouts.

Max Beckett, Uswitch broadband expert, says: 'Your broadband is only as reliable as the electricity behind it, and power cuts are now the main reason people lose their connection.

'Keep a charged mobile to hand, and if anyone in your home relies on the landline, ask your provider about a battery backup.'

Stormy weather can cause power outages and disruptions as heavy winds, falling trees and lightning strikes damage power infrastructure or trigger automatic safety shutdowns.

When these power cuts hit, they also take down broadband and landline services with them. 

As the growing Super El Niño begins to affect British weather, events like this could become more common.

Experts say the phenomenon is now pushing into unprecedented territory, with vast swathes of the planet forecast to experience unusually warm conditions as the Pacific Ocean releases enormous amounts of stored heat.

Professor Adam Scaife, head of monthly to decadal prediction at the Met Office, says he has 'never seen an El Niño signal this intense in our forecasts'.  

While El Niño doesn't directly affect British weather, experts say warm ocean temperatures in the Pacific send 'waves' rippling through the atmosphere.

These waves push the world's most powerful weather systems – including the jet stream – off their usual course, wreaking havoc on Britain's winter weather.

According to Uswitch, almost four million adults in the UK lost their broadband connection because of a storm, flood, or severe weather in the past year.

In rural areas, the effects are even more severe as power grids rely on fewer connections in closer proximity to trees, with one in eight adults experiencing a storm-related outage.

While some blackouts are brief, the majority leave homes in the dark for several hours.

Of those affected by outages last year, two-thirds – or 17.6 million people – said that they were cut off for three or more hours.

When large storms strike, huge swathes of the country can be affected, meaning that it takes even longer for power companies to restore connections.

In 2021, for example, Storm Arwen left over one million homes without electricity.

Of those, Ofgem, the national energy regulator, found that 400,000 customers were without supply for more than three days, and nearly 4,000 were off supply for over a week.

Ofgem also found that the majority of the outages were triggered when strong winds blew trees and branches into power lines.

In their report on the outages, Ofgem wrote: 'Severe weather events are likely to become more common as the effects of climate change are felt, so it is imperative that all DNOs [Distribution Network Operators] are well prepared.'

El Niño is part of a natural weather cycle, in which the trade winds that normally carry warm water westwards from the Pacific towards Australia slow or even reverse.

This leads to a buildup of warm surface water in the Equatorial Pacific, off the coast of South America, which raises the global average temperature and disrupts global weather patterns. 

This winter, experts predict the jet stream will send storms towards the UK along powerful currents of fast-moving winds.

Will Lang, chief meteorologist at the Met Office, previously told the Daily Mail: 'El Niño conditions increase the chance of storms in late autumn and early winter.'

With that increased risk of stormy weather, comes a higher chance of widespread power cuts and broadband outages.

Britons have already been warned to expect large storms this autumn and winter, with the Department for Environment, Food and Rural Affairs urging people last month to 'store a bit of food that can keep you going for a while'.

But now, Uswitch says that a charged mobile phone and a backup 4G or 5G router may be just as important for keeping you connected to friends, family and help in case of an emergency.