What Caused the Beast from the East?

In late February 2018, the UK was gripped by one of the most memorable cold spells in recent decades. Dubbed the “Beast from the East”, this event brought heavy snowfall, sub-zero temperatures, and widespread disruption across Britain. But what exactly caused it? Understanding the science behind the Beast from the East sheds light not only on that particular episode, but also on how global weather systems interact to produce extreme conditions.

The Basics: What Was the Beast from the East?

The Beast from the East was the name given to a severe cold wave that hit the UK and much of Europe between 26 February and 4 March 2018. During this period, temperatures plunged well below average, snow blanketed many parts of the country, and transport networks ground to a halt. Schools closed, flights were cancelled, and supermarket shelves emptied in some areas as supply chains struggled.

While Britain is used to bouts of wintry weather, what made this event remarkable was its intensity and the way it developed. The origins can be traced thousands of miles away in the upper atmosphere.

The Role of the Polar Vortex

At the heart of the story is the polar vortex—a large area of low pressure and extremely cold air that normally swirls high above the Arctic in winter. Under usual circumstances, this vortex keeps the coldest air locked in the polar regions.

However, in early 2018 something unusual happened: the polar vortex weakened dramatically due to a phenomenon known as sudden stratospheric warming (SSW).

Sudden Stratospheric Warming Explained

Sudden stratospheric warming occurs when the temperature in the stratosphere (around 10–50km above the Earth’s surface) suddenly rises by as much as 50°C in just a few days. This warming doesn’t affect the ground directly, but it disrupts the circulation of the polar vortex.

When the polar vortex breaks down or shifts, it allows cold Arctic air to spill southwards into Europe and Asia. At the same time, milder air is drawn northwards into the Arctic.

That’s exactly what happened in February 2018. The stratospheric warming event forced the jet stream—a fast-moving ribbon of air that usually steers weather systems west to east across the Atlantic—to buckle. This sent icy winds from Siberia sweeping across continental Europe and into the UK.

Why Did the UK Feel It So Strongly?

Several factors combined to make the Beast from the East particularly severe in the UK:

Persistent easterly winds – High pressure over Scandinavia locked the winds in place, funnelling frigid Siberian air directly towards Britain.
Moisture from the North Sea – As the cold, dry air passed over the relatively warmer waters of the North Sea, it picked up moisture. This produced heavy snow showers, especially along eastern coasts.
Blocking patterns – The jet stream’s unusual position meant that milder Atlantic weather systems couldn’t push in to dislodge the cold air. The icy conditions lingered for over a week.

The Impact Across the UK

The Beast from the East had far-reaching consequences:

Temperatures dropped as low as –14°C in some parts of Scotland.
Up to 22 inches (55cm) of snow fell in parts of the Pennines.
Major roads such as the M80 in Scotland were closed for hours, leaving motorists stranded.
Hundreds of flights and train services were cancelled.
Energy demand surged, leading to warnings of potential gas shortages.

When Storm Emma arrived from the Atlantic at the same time, colliding with the cold air, conditions worsened further. This combination led to blizzard conditions in parts of the south-west, Wales and Ireland.

Could It Happen Again?

Meteorologists confirm that sudden stratospheric warming events are not rare—they typically occur once every two years. However, not all SSW events lead to severe weather in the UK. Much depends on how the jet stream and blocking patterns evolve afterwards.

Climate change may also play a role. Some scientists suggest that as Arctic sea ice continues to decline, disruptions to the polar vortex could become more common. This might increase the chances of extreme cold snaps in Europe, even as global average temperatures rise.

Key Takeaways

So, what caused the Beast from the East?

A sudden stratospheric warming event disrupted the polar vortex.
This allowed Siberian air to flood into Europe and the UK.
The UK’s geographical position next to the moisture-rich North Sea amplified snowfall.
Blocking patterns in the jet stream locked the cold weather in place.

The Beast from the East was a perfect example of how interconnected global weather systems are. A disturbance high above the Arctic set off a chain reaction that left Britain paralysed in snow.