Motorists have been told to take extreme care on the roads over the next number of days after a severe weather warning was issued by Met Éireann.
Blizzards, freezing temperatures and gale force winds are forecast from this evening, particularly in the north and northwest of the country.
Gerry Scully of Met Éireann said: "Temperatures have been dropping steadily since this morning and it is only 3 or 4 degrees in the north now.
"There will be significant falls of snow in the north and north west," he said, but little or none in the extreme south and southeast.
But he said it would be a bitterly cold night everywhere and tomorrow would see "wintry showers of mainly sleet and snow. Northern counties will bear brunt of them".
Met Éireann has issued two weather warnings, one advising of heavy snowfall and the other that winds will reach gale force.
By Sunday the wintry showers are expected to turn back to rain in most parts, Mr Scully said.
Emma Caulfield, of AA Roadwatch warned motorists to consider postponing non-essential journeys in affected areas. "If you must travel the best advice is to expect the unexpected," she said.
She said motorists should slow down, leave more time to complete journeys and keep a safe distance from the car in front.
She added: "It is a myth to think that reducing tyre pressure helps with grip - you are far better off sticking with the manufacturer's recommendations".
For drivers who find themselves skidding on snow or ice the advice is to avoid braking suddenly, reduce acceleration but don't take the foot off the accelerator completely and use the highest gears possible under the conditions. Then, with gentle braking, move down in the gears to come to a gradual halt.
