The UK and Ireland are braced for winds reaching 80mph as Storm Dylan arrives to bring a wet and windy end to 2017.
A Met Office amber wind warning covering Northern Ireland and parts of southern and western Scotland is in place for Sunday morning and early afternoon.
Forecasters warned there was the potential for "injuries and danger to life from flying debris".
But many new year celebrations look set to escape the worst of the weather, which will pass before crowds gather to see in 2018.
In Ireland there is an orange wind warning in place from Met Eireann for nine counties, with warnings of gusts reaching 78mph (125kph).
The Met Office warned of similar gusts hitting northern parts of the UK, while Wales and southern England were on alert for heavy rain as warm, wet weather sweeps in.
Chief forecaster Steve Ramsdale said: "While the strongest winds from Storm Dylan will be over the Republic of Ireland, very strong winds will also affect Northern Ireland, southern Scotland and northern England.
"Travel disruption is likely, as well as power cuts and the chance of tiles being blown off roofs. Large waves and coastal debris may also be another hazard in coastal districts."
After heavy snow, rain, thunderstorms and wind caused disruption across much of Britain on Friday as the country was gripped by wintry weather, Saturday saw milder temperatures begin to appear as the storm approached.
Met Eireann warned that Dylan would pass close to the country's north-west coast, bringing wintry showers as temperatures dropped as low as 2C (36F).
A spokesman warned of rain becoming widespread late on Saturday and into Sunday morning.
He said: "In the north it will be heaviest, with a risk of thunder, and will fall as snow and sleet over the hills and mountains. Coastal flooding is expected along the west coast as high seas coincide with low tide and onshore winds."
There were also yellow wind warnings in place for the rest of Scotland south of Dundee, plus north east and north west England. However, the winds are expected to ease into the afternoon as the storm moves north west across Britain.
There is also a yellow warning for rain in Wales, south east and south west England on Saturday night and into Sunday morning.
Some areas are likely to see up to 40mm falling in the space of three hours, the Met Office said, causing possible transport disruption due to surface water and spray, and the potential for localised flooding.
However, revellers heading out to see in 2018 may escape the worst of the weather.
Large-scale celebrations are planned for cities including London and Edinburgh.
Mr Ramsdale added: "In many places, there is a good chance of dry weather for outdoor celebrations seeing in the new year.
"New Year's Day will feature wintry showers in the north and the unsettled weather looks likely to continue through the first week of January, with further bouts of wet and windy weather. In particular some very strong and gusty winds, together with thundery downpours, are likely on Wednesday and may cause some disruption."
Organisers of Edinburgh's Hogmanay celebrations expect the event to go ahead in full.
A spokeswoman for Underbelly, the event organisers, said: "Edinburgh's Hogmanay is, as always, in constant contact with the Met Office, receiving regular forecast updates specific to Edinburgh.
"Forecasters are predicting that Storm Dylan will hit Scotland's central belt between midnight and 3pm on December 31, happening after the torchlight procession on December 30 and passing before the Hogmanay celebrations on December 31."