Why is it so heat within the UK? Confused Brits query the surprisingly balmy December climate – as temperatures in London hit 12°C

A strange wave of warm weather has left Britons sweltering in their winter coats and switching off the heating.

As temperatures climb to 12°C (53.6°F) in London, baffled Brits have flocked to social media to question the strangely balmy December weather.

On X, one confused commenter asked: ‘Is nobody concerned with how WARM it is in the middle of December for London?’

Hundreds of Brits have raised a similar point, with one complaining: ‘I hate the cold but it’s so concerning that it’s not actually been that cold this autumn/winter.’

‘I’m literally walking around with no coat on bc im so hot lol,’ added another.

While one Brit chimed in: ‘It does seem like Decembers have got noticeably milder in the last few years, and the really severe cold snaps are not seen until January and February. White Christmases seem like a distant memory now.’

Now, meteorologists have revealed the real reason why the build–up to Christmas has been unseasonably warm.

And the good news is that things may cool down just in time for you to break out the Christmas jumpers.

As temperatures climb to 12°C (53.6°F) in London, baffled Brits have flocked to social media to question the strangely balmy December weather

On X, one commenter asked whether anyone else was concerned about how mild the weather had been this December 

Average temperatures for December in the UK (right) are typically anywhere between 2°C and 8°C (35–46°F), but have remained significantly higher than average. This has sparked a wave of confusion on social media 

Average temperatures for December in the UK are typically anywhere between 2°C and 8°C (35–46°F), depending on your location in the country.

However, the first two weeks of December have already seen temperatures climbing well above their normal limits.

In some parts of the country, temperatures have risen as high as 15°C (59°F), while conditions have rarely fallen below freezing.

These warm conditions have caused a great deal of confusion on social media over the last few days.

In one post on TikTok, a user complained: ‘It’s currently the middle of December in London, and I am walking to work in just my shirt because it’s so warm.

‘There’s no hope of a white Christmas this year people. I am just sick of this mild weather.’

Another posted: ‘Guys why is it so warm in England rn? Its 12 12°C (54°F) and I don’t even have a jacket. Normally its like 0°C around this time.’

Meanwhile another complained that they were ‘overheating entering any building atm’.

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Is Britain’s unusually warm December a wake-up call about climate change, or just a seasonal blip?

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Brits have taken to social media to point out that the weather has been warm enough to ditch their normal winter coats

One commenter said that, as much as they hated the cold, they found it ‘concerning’ to see such warm weather in the winter

Another joked that they were ‘walking around with no coat on’ because the recent weather had been so hot 

Why has it been so warm in the UK?

Britain’s recent spell of warm weather is due to a strong North Atlantic jet stream, driving a series of low–pressure systems northeastwards across the Atlantic.

These low–pressure systems bring mild air and warmer temperatures, but also lead to heavy rainfall and strong winds.

Meteorologists say the strong jet stream has been caused by the intense cold weather over northeastern America and Canada.  

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According to meteorologists, Britain’s warm weather has its origins all the way across the Atlantic.

Jim Dale, senior meteorologist at British Weather Services and co–author of ‘Surviving Extreme Weather’, told Daily Mail that the UK is currently facing an unusually energetic jet stream.

This is the system of fast–moving air flowing about five to seven miles above the ground that steers weather fronts and low–pressure systems towards the UK.

Since November, Mr Dale says that the jet stream has been ‘more or less over us’, causing a wave of warm, wet, and windy weather.

‘One of the reasons we’re getting that is because of the cold weather in the northeastern United States and Canada,’ says Mr Dale.

‘When that cold air sits in situ, it blows out into the Atlantic where it meets mild air and energises the jet stream, and that produces these low–pressure systems.’

That is also part of the reason the UK has been facing a barrage of heavy rainfall and stormy weather, including Storm Bram, over the last few weeks.

The good news is that current forecasts suggest that these low–pressure systems should abate in the coming weeks.

Meteorologists say that the recent warm weather is due to a strong northeasterly jet stream over the Atlantic, driven by the extremely cold weather over the northern United States  

In addition to making the weather warmer, this jet stream has also brought low–pressure fronts that have driven storms that have caused flooding in towns such as York (pictured) 

The Met Office forecast says: ‘A large area of high pressure is expected to build closer to the UK from around the 22nd of December.

‘With high pressure in charge, the weather is likely to settle down, bringing clearer skies at night and the potential for frost and fog patches.

‘This means that Christmas Day itself is looking drier and perhaps a little colder compared to the first half of December.’

However, although the Met Office says that an active jet stream is to blame for our recent spell of warm weather, seasons like this are going to be more likely in the future.

A Met Office spokesperson told Daily Mail: ‘It’s not possible to attribute the current mild period to climate change without a formal attribution study. However, we know that as a result of human–induced climate change, we see more frequent warmer weather, and that remains true in winter.’

Six of the ten warmest winters on record, dating back to 1884, have occurred since the start of the 21st century.

Likewise, 2025 is already firmly on track to be one of the three hottest years on record.

The spokesperson adds: ‘This obviously doesn’t mean that we won’t see colder periods, but that the background influence of global warming means we generally see warmer winters than we used to.’

WHAT IS A JET STREAM?

Jet streams are fast flowing, narrow currents of air that carry warm and cold air across the planet, much like the currents of a river.

They cover thousands of miles as they meander near the tropopause layer of our atmosphere.

They are found in the atmosphere’s upper levels and are narrow bands of wind that blow west to east.

The strongest jet streams are the polar jets, found 30,000 to 39,000 ft (5.7 to 7.4 miles/ 9 to 12 km) above sea level at the north and south pole.

In the case of the Arctic polar jet this fast moving band of air sits between the cold Arctic air to the north and the warm, tropical air to the south.

When uneven masses of hot and cold meet, the resulting pressure difference causes winds to form.

During winter, the jet stream tends to be at its strongest because of the marked temperature contrast between the warm and cold air.

The bigger the temperature difference between the Arctic and tropical air mass, the stronger the winds of the jet stream become.

Sometimes the flow changes direction and goes north and south.

Jet streams are strongest – in both the southern and northern hemispheres – during winters.

This is because boundaries between cold and hot air are the most pronounced during the winter, according to the National Weather Service (NWS).

The direction the air travels is linked to its momentum as it pushes away from the earth’s equator.

‘The reason has to do with momentum and how fast a location on or above the earth moves relative to earth’s axis,’ NWS explains.

The complex interactions of many factors, including low and high pressure systems, seasonal changes and cold and warm air – affect jet streams.