Parts of the UK are expected to be battered by winds of up to 100mph when Storm Arwen arrives later.
The Met Office has issued a red warning the highest level, which is issued only rarely, meaning there is potentially a risk to life.
Gusts of wind could be as high as 100mph parts of north-east England and Scotland, running from 15:00 to 02:00 GMT on Saturday.
Elsewhere there is an amber warning, with winds of 60 to 75mph.
People have been urged to check on elderly neighbours or relatives and put off journeys if possible.
A red warning means dangerous weather is expected and people should take action immediately to keep themselves and others safe from the potential impacts.
There is also an amber warning – meaning damage and travel disruption – for other parts of Scotland and north-east England, and a yellow warning for Northern Ireland, Wales and south-west England.
The Met Office said the winds could mean:
Flying debris resulting in danger to life.
Damage to buildings and homes, with roofs blown off and power lines brought down.
Roads, bridges and railway lines closed, with delays and cancellations to bus, train, ferry services and flights.
Power cuts affecting other services, such as mobile phone coverage.
Large waves and beach material being thrown on to coastal roads, seafronts and homes.
People are being urged to take precautions, with Northumberland Fire and Rescue Service urging them to secure loose items outdoors.
The UK Health Security Agency (UKHSA) has urged people to check on elderly relatives or neighbours.
A spokesperson said: “Cold weather can have a serious impact on health, particularly for older people and those with heart and lung problems, as it increases the risks of heart attacks, strokes and chest infections.
“Make a call, or a socially-distanced doorstep visit if they live close by, to remind them to heat their home to at least 18C (64.4F) …. and check they have enough food and drinks and any medicines they need.”
Rod Dennis, from the RAC, said a red warning was “the strongest possible signal to drivers not to set out in the first place unless absolutely necessary”.He added: “Drivers in those parts of the UK covered by amber weather warnings should also consider postponing their planned trips until the storm passes.
“As well as making driving much more challenging, strong winds cause an increased risk of trees and powerlines falling – add snow into the equation and the risks increase significantly.”
Storm Arwen, the first named storm of the year, is moving south down from Scotland.
BBC Look North weather presenter Jennifer Bartram said: “It is likely to cause damage and transport disruption.
“Coastal flooding is less likely, as we don’t have spring tides at the moment, but it will be very dangerous with large waves nonetheless.”
The RNL has warned people should be extremely careful if visiting the shoreline, especially along exposed cliffs, seafronts and piers.