MET ÉIREANN'S Status Yellow warning for the entire country has come into effect with snow, ice and wintry showers expected nationwide.
The warning came into effect at 6am and will remain in place until 9am on Wednesday.
People around the country have told to brace for icy conditions as well as hail and sleet which will become increasingly widespread throughout the day.
In parts of the country, including Dublin, have also been issued with thunder warnings.
AA Roadwatch is reminding motorists that it takes much longer to stop a vehicle when roads are icy and are advising motorists to reduce speed and keep further back from the driver in front.
"Avoid any harsh acceleration or braking, and allow extra time to fully de-ice your vehicle before setting out," it warned.
During the night, the mercury is expected to drop to below freezing, dropping to temperates of -2C in places.
The full forecast from Met Eireann says: "Tuesday will be a cold and windy day, with sunny spells and widespread blustery showers.
"Some of the showers will have a wintry mix of hail and sleet, with the risk of some snow showers, mainly over high ground.
"There is also a risk of thunder. Daytime highs of just 3 to 6 degrees, in mainly moderate to fresh westerly winds, but winds will increase strong to gale force and gusty near Atlantic coasts later."
Wednesday and Thursday are thought to be a little warmer, with temperatures rising to around 7 or 8 degrees in the day.
But the cold is expected to return once the sun goes down, with "outbreaks of rain extending from the Atlantic, possibly falling as sleet, and hill snow, for a time in the north and northwest, but very patchy in Munster and south Leinster," according to the forecaster.