Met Éireann has extended a status red snow-ice alert for the entire country.
It is in place into Friday afternoon.
Met Éireann says further heavy snow showers will see accumulations of significant levels - with all areas at risk.
"Blizzard conditions will develop from the south Thursday afternoon and evening as heavy snow and strong easterly winds bring snow drifts northwards over the country. Eastern and southern coastal counties will be worst affected."
Earlier, lower-level status orange and yellow warnings were in place for other parts of the country.
The Taoiseach Leo Varadkar said the country is prepared for the storm to come:
“I want to assure the Irish people that while we are hoping for the best, we are of course preparing for the worst and we will be ready for whatever the weather brings,” he said.
“I would ask people to look after their neighbours, especially those who are isolated or living alone; to look after the elderly; to look after each other.”
Harold's Cross Park. Image: Mick Staines
The arrival of Storm Emma tomorrow is set to bring more heavy snowfall and gale force winds in the coming days.
The weather has led to major transport disruption, some schools have closed, and court sittings have been cancelled in Dublin.
The Minister for Education has said decisions on school closures will be made locally by individual schools.
Further updates are expected throughout the day:
Advice today: Decisions on school closures will be made locally by each school individually depending on the circumstances in their area, this includes schools in the red areas. We will continue to monitor the situation and update further throughout the day #beastfromtheeast
— Richard Bruton (@RichardbrutonTD) February 28, 2018
Most third level institutions in Dublin have announced that they are closed for the day.
UCD and DCU are among those that are closed, but Trinity College says it is open:
— TrinityCollegeDublin (@tcddublin) February 28, 2018
Update: ALL DCU CAMPUSES ARE NOW CLOSED AND CLASSES CANCELLED until Monday 5th March. Facilities closed just as today. Check back for any further developments. Stay safe and warm everyone! ðŸŒ¨ #BeastFromTheEast
— DCU (@DublinCityUni) February 28, 2018
Griffith College campuses in both Dublin and Cork are also closed:
So this is the view from @GriffithCollege this morning. Classes cancelled in our Dublin and Cork campuses (including evening classes). We will update later today about tomorrow's classes. https://t.co/j2XQeDfWvE pic.twitter.com/9gvSETgNfm
— Griffith College (@griffithcollege) February 28, 2018
Many public transport services are either not running on Thursday or have a curtailed service in place.
Earlier more than 200 flights in and out of Dublin Airport were cancelled.
Operations were suspended for a brief period this morning as crews worked to clear the runways, and only a handful of flights have departed today.
Large crowds gathered in the terminals waiting for updates.
— Paul Quinn (@pdquinn7) February 28, 2018
The DAA is advising passengers to contact their airlines for the latest flight information.
— Tom Swift (@tomswift111) February 28, 2018
All flights to/from Dublin Airport have been cancelled for the remainder of the day, 28th Feb 2018. All affected customers will be notified of their options by email / SMS text message. pic.twitter.com/DaPqqRtKKY
— Ryanair (@Ryanair) February 28, 2018
Cork Airport says operations were suspended until at least 12pm "to allow for further clearing of snow from the runway and taxiway".
The Government has confirmed it will double the fuel allowance for this week.
Around 330,000 people will benefit from the extra €22.50 this week to heat their homes, according to Social Protection Minister Regina Doherty.
She noted that the payments may not get the payments for a week or two, but stressed everyone receiving the allowance will receive it in the coming weeks.
People are being urged to make sure their homes are heated safely during the cold weather.
The public is being reminded to ensure proper ventilation and keep an eye on open fires.
Marguerite Cotter from Phonewatch has some advice for doing it safely:
"Make sure you use the fire guard," she said.
"Don't leave the fire overly flaiming when you are going to bed; if you are using heaters, make sure you don't cover them.
"The vent is a big one; make sure you don't cover the vents when it is very cold.
"Then it is important to make sure your smoke and you carbon monoxide alarms are working well."