'Weather bomb' conditions explained as Storm Eowyn heads to UK

The Met Office has warned of an impending ‘weather bomb’ as Storm Eowyn arrives in the UK this weekend.

With rare red weather warnings in place in Scotland and Northern Ireland for wind and different alerts covering the whole of the country forecasters have said gusts could reach speeds of 100mph, while heavy rain could cause flooding in some areas.

Widespread disruption is expected on the roads, railways and air, while ferry crossings will also be affected by Eowyn, which could be one of the most disruptive weather events of 2025.

The Met Office has warned that the weather bomb will create “exceptionally dangerous” conditions in some areas covered by the red weather alert.

The change to conditions is being caused by a powerful jet stream pushing the low pressure across the Atlantic and towards the UK, following a recent cold spell over North America, the Met Office said.

What is a weather bomb?

A weather bomb is a less technical term for what is officially known as an explosive cyclogenesis.

Essentially it is a dramatic weather event where a low-pressure system intensifies rapidly when the central pressure of a storm drops at least 24 millibars in 24 hours, leading to a sudden and significant strengthening of the storm.

The rapid acceleration of air caused by the jet stream high up in the atmosphere can remove air from the column, reducing its weight and causing pressure to fall at sea level.

Once this happens, air is sucked in from surrounding regions, resulting in a faster rotation – creating a peak of violent winds that are strong enough to bring down trees and cause structural damage, according to the Met Office.

To put it in simpler terms, if the atmosphere was a huge whirlpool, a weather bomb would make it spin faster because of the cold air rushing in and colliding with warmer air at sea level – sparking strong winds.

A weather bomb has the ability to turn what is a manageable storm into something far more ferocious, dangerous and violent within a matter of hours.

This rapid development can lead to extreme weather conditions, including hurricane-force winds, heavy rainfall, or even heavy snowfall if the air is cold enough.

We are seeing this play out this week ahead of Storm Eowyn – the weather bomb has sparked the Met Office to continuously upgrade its weather warnings, which have gone from yellow to red as the storm's arrival grows closer.

Professor of geography from Maynooth University, Peter Thorne, said extreme cold in southern US states crashing into high temperatures in the north Atlantic have “supercharged the atmospheric jet”.

He added: “This storm [Eowyn] has then coupled with that jet ‘just so’ to enable very explosive cyclogenesis.”

Storm Eowyn weather warnings

Such is the strength of Storm Eowyn, Northern Ireland and parts of Scotland are subject to rare red weather warnings. The warnings are effective from 7am to 2pm in Northern Ireland and from 10am to 5pm in southern Scotland on Friday.

Amber and yellow warnings for wind, rain and snow are also in place for Friday, with the whole country affected by Eowyn.

The Met Office anticipates peak rush hour wind speeds of 80-90mph across Northern Ireland, with gusts potentially reaching 100mph in exposed areas. These winds are expected to cause flying debris, posing a danger to life, and create “very dangerous” driving conditions due to fallen trees.

Dr Jess Neumann, associate professor of hydrology at the University of Reading, said: “Storm Eowyn is not one to underestimate – stay safe, stay prepared, and plan ahead. This storm has the potential to bring serious risks, not just to travel and property, but to your safety and wellbeing.”

Watch: Red warning for wind issued across Ireland and parts of Scotland