Two red snow and ice warnings are in place around the country.
A status red snow-ice warning is in place for Connacht, Cavan, Monaghan and Donegal until 6.00am on Friday.
Met Éireann says sub-zero temperatures and icy conditions will continue tonight in strong easterly winds - with heavy snow showers and high accumulations in some areas.
While a separate, extended status red snow-ice warning has been issued for Munster and Leinster.
The forecaster says there will be blizzard conditions tonight and during Friday in Leinster and Munster.
It says that southern and eastern coastal counties are expected to receive "exceptionally high accumulations."
This alert is in place until 6.00pm on Friday.
Severe Weather Warnings Update: https://t.co/9BeK3UcAwO
— Met Éireann (@MetEireann) March 1, 2018
People being warned to not go outside until it has been lifted tomorrow.
The blizzard is making its way across the country with the east the worst affected.
Taoiseach Leo Varadkar appealed to people to heed the advice and stay inside.
Taoiseach Leo Varadkar says Ireland has a great community spirit and people should check on the sick, the old, the vulnerable and those living on their own. #BeastFromTheEast pic.twitter.com/PrHAwjdsLm
— Today FM News (@TodayFMNews) March 1, 2018
Visibility will be almost non existent with wind chill factors of -15.
All forms of public transport has been affected with most services not expected to resume until Saturday.
All schools, colleges and third level institutions will be closed today and tomorrow as will all the courts.
People are being reminded to have a working torch and some candles on standby in case of a power outage during Storm Emma.
The ESB has asked customers to check if their fault has already been reported on powercheck.ie before they call.
Electricity went out for a time this morning in hundreds of homes in Dublin, Cork and Kerry.
Good morning from HQ ðŸŒ¨ï¸ pic.twitter.com/YXj6WoPLt6
— Met Éireann (@MetEireann) March 1, 2018
1/2 Scattered heavy snow showers and widespread ice and lying snow today. During the afternoon and evening blizzard conditions will develop across Munster and Leinster as heavy snow together with driving easterly winds spread northwards to all areas through the rest of the day. pic.twitter.com/Me8mivOPki
— Met Éireann (@MetEireann) March 1, 2018
All outpatient appointments and planned admissions at the three children's hospitals today have been cancelled.
Anyone who attends the emergency departments at Temple Street, Crumlin or Tallaght hospitals will be seen.
Meanwhile, the ISPCC's Childline service has had to close.
Regrettably, @ISPCCChildline has had to close its services until safe to re-open. This is as a result of the Status Red National Weather Warning. Any child in need of immediate help should contact emergency services at 999 or 112. https://t.co/lRAVSmGMnV. #StormEmma
— ISPCC Childline (@ISPCCChildline) March 1, 2018
It's only the second time the service has been forced to close in 30 years.