Coastal areas across the UK are braced for the impact of Storm Barra later, while a rare red alert has been issued in the Republic of Ireland.
The highest level of Irish weather service Met Éireann's warning affects counties Clare, Cork and Kerry, and schools are to close in 12 counties.
It warns of severe and damaging gusts of more than 130km/h (80mph).
Disruptive wind and some snow are expected in parts of northern England and Scotland, said the Met Office.
Some flights have been cancelled, driving conditions are set to be difficult and there are fears of damage to buildings, power cuts and flooding.
The second named storm this season, Storm Barra comes just 10 days after Storm Arwen struck on 26 November, causing disruption and three fatalities across the UK.
Met Éireann has warned Storm Barra will likely cause coastal flooding along parts of the south and western Irish coast, while disruption to power and travel is also likely.
With a status orange warning - the second-highest level - in place for Clare, Limerick and Galway, and a yellow warning for all other counties, it has urged people to take action to protect themselves and their homes.
A cold start with some icy stretches #Tuesday morning 📉🌡️ #StormBarra quickly arrives from the west with heavy rain and gales for most, severe gales and snow for some🌧️🌧️❄️🌬️🌬️— Met Office (@metoffice) December 6, 2021
Weather warnings are in place⚠️
Stay #WeatherAware pic.twitter.com/xWqm7LNzGH
A Met Office yellow warning for Northern Ireland has been issued from 06:00 GMT on Tuesday to 09:00 on Wednesday.
The strongest gusts will affect exposed and coastal areas, with potentially damaging and disruptive winds up to 80km/h (50mph) expected widely.
The Met Office says winds are likely to be strongest in the region along the coasts of counties Down and Antrim where large waves could cause disruption.
Gusts around the coast could reach speeds of 120km/h (75 mph).
Heavy and persistent rain on Tuesday morning will be followed by frequent and heavy showers into Wednesday.
Up to 30mm of rain is forecast quite widely, while higher ground could get as much as 50mm.
The Royal National Lifeboat Institution (RNLI) has appealed for people to stay well back from the water's edge due to the risk of large waves, and in any coastal emergency to dial 999 for the coastguard.
Cancellations and closures
The Irish Department of Education has advised that all schools covered by an orange or red warning should shut on Tuesday - which covers 12 counties.
Schools in other areas should keep up-to-date with weather warnings for any changes, the department said.
University College Cork will also be closed as will the Covid-19 vaccination clinic at Cork City Hall.
An Garda Síochána (Irish police) are advising people to avoid all unnecessary travel where red and orange warnings are in place.
With the arrival of #StormBarra tomorrow, we continue to advise that all unnecessary travel should be avoided where Red and Orange warnings are in place— An Garda Síochána (@GardaTraffic) December 6, 2021
We advise the public to regularly monitor https://t.co/TJBfRQ159T for further updates over the next two days https://t.co/YPUJYgYoR8
Flight operator Aer Lingus has already cancelled some early morning services on Tuesday, including flights from Cork to Amsterdam and London Heathrow.
Customers are advised to check with the airline for further information.
With #StormBarra on the way, 60-70mph gusts are expected in coastal locations. #RespectTheWater by staying well back from the water's edge and in any coastal emergency dial 999 for the Coastguard. If you end up in the water, stay calm and #FloatToLive. pic.twitter.com/2mscNadUy8— RNLI (@RNLI) December 6, 2021
Victoria Park in east Belfast will be closed from 06:00 GMT until 09:00 on Tuesday, Belfast City Council confirmed.
Some events have been cancelled too, including the Christmas market in Cork, planned for Tuesday at Macroom Town Square.