Strong winds, wintry showers and fallen trees are making driving conditions difficult, drivers have been warned.
AA Roadwatch said motorists travelling home for Christmas should take extreme care on all roads, particularly in the west of the country
"Remember high-sided vehicles are particularly vulnerable on open or exposed roads," it added.
Several ferry sailings have been cancelled due to adverse conditions on the Irish Sea.
Met Eireann has forecast severe gusts which will ease during the day. Temperatures will drop to as low as minus one degree overnight.
Gardai and road safety chiefs have urged motorists to drive with extra care and not to speed or drink drive.
A total of 183 people have been killed on Irish roads so far this year.
The latest victim, a man in his 40s, died when his car hit a wall at Moyleen, near Loughrea, at around 2pm yesterday.
His nine-year-old son was also injured in the crash
Gardai in Galway are warning of severe strong winds, particularly on the M6 Dublin/ Galway Rd westbound between J18 and J19.
A car overturned on the old Dublin Road near Furey's Cross and fallen trees are partially blocking the N59 Galway/Clifden Road in Moycullen and t he N63 Roscommon/Longford Road.
There is also debris on the N11 Dublin/Wexford Road between J9 and J10, slushy road conditions around Ballymote in Sligo, Bandon in Cork, Glenade in Leitrim, and snow on roads around Cavan town.
Elsewhere Irish Water Safety has warned thousands of Christmas Day charity swimmers nationwide to be aware of the condition "cold shock".
"Cold winter waters can cause 'cold shock' and hypothermia can set in within minutes, overwhelming the fittest of swimmers," it said.
"If sea conditions deteriorate then the charity swim should be cancelled."
It warned many participants will not have swum since the summer and the temperature of the water has now dropped considerably.
"It is a fallacy that alcohol will keep you warm when entering the water; in fact it has the reverse effect and could kill you," it added.
The Irish Coast Guard warned people to be extra careful in sea areas after a gale warning was issued for the Atlantic coast.
Storm force 10 gusts are expected in some areas resulting in heavy swells.
The Coast Guard advised members of the public not to go out on exposed coasts, cliffs, piers, harbour walls, beaches, promenades or any other coastal areas.
"These waves can pose hazards to anyone close to the shoreline," it said.
"It is important to be especially vigilant over the festive period where people are engaged in outdoor activities in areas and environments they may not be familiar with and the onset of inclement weather ever present."
The ESB said a bout 6,000 homes and businesses in the Achill area are without electricity because of lightning.
Power to another 11,000 customers in west Galway has been restored, a spokeswoman added.