We're being warned to expect snow and sub-zero temperatures this weekend.
A status orange warning for snow and ice has been issued for Dublin, Kildare, Louth, Wexford, Wicklow, Meath and Waterford for Sunday.
Scattered heavy snow showers will lead to accumulations in places and some drifting.
Meanwhile, a status yellow alert will be in effect for the whole country from tomorrow afternoon.
Hundreds of thousands of people are due to attend parades, with several road closures in place.
“I don't think there’s any problem for the parades,” said forecaster John Eagleton.
“The problem will be Saturday night, Sunday morning but a lot of the activity will decrease then because it’s a bank holiday weekend.
“But don’t be surprised to see a few centimetres of snow on Sunday morning.”
People are being urged to take care on the roads this weekend.
Met Éireann is predicting up to 6cm of snow, while temperatures will plummet with the risk of frost and ice.
A status yellow weather warning is now in place for Leinster, Cavan, Monaghan and Waterford.
Hundreds of thousands of people are due to attend St Patrick’s Day Parades, with several road closures in place.
With extra volumes on many roads, motorists are being reminded to take their time, and plan their journeys ahead of the bank holiday weekend.
People are also reminded to use public transport as much as possible.
“A lot of people can be out and about, they’ve got a lot to be doing on St Patrick’s Day, a lot of things to look forward to,” said Adrian Harmon from AA Roadwatch.
“It can be very busy and a stressful time as well, so it’s just important to give yourself time to head out on the roads, drive slowly, and be mindful of the poor conditions that are expected by Met Éireann over the weekend.”
People heading along to St Patrick's Day parades are being urged to wrap up.
Temperatures are set to plummet with snow and ice expected in parts of the country this weekend.
Forecasters have issued a Status Yellow weather warning for Leinster, Cavan and Monaghan where they expect low-temperatures and snow showers on Saturday night and Sunday.
Met Eireann forecaster Klara Finkele said: "Temperatures will gradually fall through the entire period, so by tomorrow morning we will see around three or four degrees on the east coast.
"Tomorrow's temperatures in the afternoon will be just around 1C to 2C, so it will be quite cold. Especially on the eastern side of Ireland, 1C to 2C with a significant wind-chill factor.
"Rain showers in the morning turning wintry through the day.
You would be as well to wrap up or to watch the parade from home, from the lounge room.