The Met Office has extended its amber wind alerts to cover most of the UK in a rare move ahead of Storm Isha tonight - warning of potential "danger to life" in some areas.
Storm Isha, the ninth since September, is expected to bring winds of up to 80mph, potentially causing power cuts and increased congestion as roads and bridges are likely to be shut, while rail and bus services could face delays and cancellations.
Two 12-hour amber wind warnings will be in place from 6pm on Sunday until Monday morning. One stretches across central, eastern and western England and all of Wales, only missing London and parts of the South East.
According to the Met Office, the amber warnings mean:
A good chance of power cuts, with the potential to affect other services such as mobile phone coverage
Probably some damage to buildings, such as tiles blown from roofs. In the northern warning, the Met says roofs could be blown off and power lines brought down
Longer journey times and cancellations likely, as road, rail, air and ferry services may be affected
Some roads and bridges likely to close
Injuries and danger to life likely from large waves and beach material being thrown onto coastal roads, sea fronts and properties
Flying debris could result in danger to life
Yellow warnings for rain are also in place across the country over the next two days, as well as eight flood warnings and 58 flood alerts in England.
The heaviest rain is expected today, with 30mm to 50mm in many places and 80mm to 100mm in hillier areas.
Met Office forecaster Ellie Glaisyer said: "The main thing about this storm is it is very widespread across the whole of the UK.
"Quite often we see storms affecting the northwest or the southern half of the UK, whereas this one, later on Sunday and into Monday, the whole of the UK is covered by a warning, which is relatively rare.
"In that nature it's a very widespread storm and it's going to be affecting everybody. Heavy rain will affect everybody, those strong winds will affect everybody.
"That's the main difference to previous storms we have seen."
Ireland's Met Eireann also has amber wind warnings in place today and on Monday, with a status red storm warning covering coastal areas in the north of the country.
"A status red severe weather warning is rarely issued but when it is, people in the areas expected to be affected should take action to protect themselves and/or their properties," the forecaster says on its website.
High winds forced the Severn Bridge to close in both directions for a time overnight, but it has now reopened.
East Midlands Railway said it expected "significant disruption" on Sunday and Monday, while Police Scotland advised people to avoid unnecessary travel.
Ms Glaisyer said: "Anybody driving on Sunday evening and through Monday should be wary of water on the roads, lots of spray, perhaps some branches and trees may have fallen over causing roads to be blocked.
"There's some large waves as well that could cause disruption to ferry services and the strong winds could cause some delays to trains and plane travel."
Warmer weather will accompany the adverse conditions after a week of snow and sub-zero temperatures, with highs of 13C possible today.
However, Met Office meteorologist Alex Burkill said the strong winds, rain and clouds could overshadow the milder weather so it might not "feel quite so warm".
Mr Burkill added: "Temperatures will be on the mild side, lifting as we go through this weekend and staying mild through much of next week.
"There may be some chillier spells but I think that any frost is likely to be isolated if we see any at all."
From Tuesday afternoon until midday on Wednesday, a yellow wind warning will be in place covering Northern Ireland, north Wales, northern England and much of Scotland.