Almost the whole of the UK is under amber weather warnings for strong winds from Storm Isha.
The Met Office said amber wind warnings will be in force from 18:00 GMT on Sunday for all of the UK apart from London and parts of the South East.
Gusts of up to 80mph (128km/h) are expected, posing a risk to life. The Met Office said it was rare for all of the UK to be under such an alert.
BBC Weather’s Matt Taylor said the disruption will continue into Monday.
Two amber warnings will be in place from 18:00. One stretches across central, eastern and western England and all of Wales.
The other covers all of Scotland, northern England and Northern Ireland.
The Republic of Ireland’s weather service Met Éireann has issued a red warning – its highest – for wind in the north-west of the country.
It said Isha would bring “severe and destructive gusts, particularly in coastal and exposed areas”.
BBC Weather’s Matt Taylor said “widespread gales” are expected across the UK by the end of the day.
Gusts of 50 to 60mph will be felt widely across the UK, with 70 to 80mph around some coasts. Across Scotland, Northern Ireland and the far north of England there is a smaller risk of 90mph winds.
At Capel Curig, Snowdonia, gusts reached 80mph on Sunday afternoon.
Additionally, there are yellow warnings for rain that cover the whole of the UK including London and parts of the South East not subject to the amber wind alerts.
He warned that disruption could continue well into Monday and the rush hour back to work.
Mr Taylor added that Storm Isha was a low-pressure weather system that brought heavy snowfall to the north-eastern US at the end of last week, and has developed as it crossed the Atlantic.
Storm Isha has developed into a large low-pressure system as it crossed the Atlantic
The Met Office saidthat there was a good chance of power cuts, which could affect mobile phone signal in affected areas, while roads and bridges are likely to be shut. Rail and bus services could face delays and cancellations.
It continued that there was a risk to life in coastal areas from large waves and debris being blown inland.
As part of wider guidance, it has also warned people to minimise risk by staying away from windows whilst at home.
Rail companies including Avanti, LNER and Transpennine said the storm would affect their services and warned customers not to travel on Sunday.
Southeastern has cancelled early Monday trains before 06:00 into and out of London to allow engineers to check for debris.
ScotRail said it was ending services outside the central belt of Scotland after 19:00 on Sunday.
Other rail lines are advising travellers to avoid travelling during the storm.
Ferry companies meanwhile announced a series of cancellations. Irish Ferries said sailings between Holyhead and Dublin and between Pembroke and Rosslare were cancelled.
DFDS meanwhile said Dover, Calais and Dunkirk services were operating with delays, and the service between Newcastle and Amsterdam was also likely to face delays.
A spokesman for the Energy Networks Association, which represents Britain’s operators, said on Friday: “An amber warning brings an increased risk of damage to homes and vital infrastructure.
“Energy network operators are preparing to deal with any damage quickly and safely.”
BBC forecaster Matt Taylor looks at the potential impacts of the storm
The heaviest downpours may occur on Sunday as 30mm-50mm could fall in many places – and there is potential for peaks of 80mm-100mm over hills.
The Met Office has said heavy rain could lead to flooding this week. As of 12:00 on Sunday, the Environment Agency had issued eight flood warnings, where flooding is expected in England, and 59 flood alerts, where flooding is possible.
After days of freezing temperatures and snow in some parts of the UK, higher temperatures are expected by the end of the weekend – but the Met Office has warned it may not feel warmer due to high winds.
Storm Isha follows Storm Henk, which hit the UK earlier this month, causing flooding and disruption, and is the ninth named storm since September.
The Met Office names storms when they have the potential to cause disruption or damage. The agency says it is easier for people to follow the progress of a storm on TV, radio or social media if it has a name.
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