There is widespread flooding and power outages after Storm Frank caused havoc across the country.
The Atlantic coast has been among the worst areas affected - with 70 millimetres of rain and gusts of up to 120km/h.
Many roads are closed, and a number of ferry sailings have been cancelled. Some rail services were also disrupted.
The National Co-Ordination Group met this morning to discuss the flood response.
The Environment Minister says flooding overnight has hit areas which had not been previously flooded.
Alan Kelly and The Minister of State at the OPW, Simon Harris, will both travel to Athlone today to asses the extent of the damage.
Minister Kelly says the situation is now worse than in recent weeks:
In a statement, the Office of Public Works (OPW) says "we remain in a severe flooding situation on the Shannon catchment and many of the above other catchments. Ongoing flood defence efforts (for example pumping) will have to continue for some time yet".
Met Éireann has a status orange wind warning in place for the country until 2pm, advising of severe winds of 65 to 80 km/h with 'damaging' gusts up to 130 km/h.
— Newstalk 106-108fm (@NewstalkFM) December 30, 2015
14,000 homes and businesses are without power after Storm Frank as of lunchtime today.
The majority of these are in Cork - 1,300 customers are in the dark in Macroom, and 600 in Cobh.
Elsewhere, more than 1,200 premises are without power in Athlone, with 800 in Tramore
There was a major fault in Celbridge in Co Kildare this morning, which left more than 4,600 customers without power.
Details of affected areas can be found on the ESB Power Check website.
Spokesperson for the ESB Paul Hand says crews hope to have all power restored by this evening.
ESB Networks is reminding people never to go near or touch fallen electricity lines, and to contact 1850-372-999 if they come across any fallen poles or lines.
Meanwhile the Coast Guard say they've recieved numerous calls from the public reporting people getting into difficulty on the shoreline in North Dublin.
They say that a number of families, some with young children, have gotten into difficulty - however no one has been seriously hurt.
Cork is among the areas of the country worst hit by Storm Frank, and emergency services and county council workers were inundated last night, with several areas under water.
Bandon, Macroom and Glanmire have all reported serious flooding.
— Richard Chambers (@newschambers) December 30, 2015
Cork County Council's emergency number can be reached on 021-480-0048 today.
Southern Correspondent with the Irish Independent Ralph Riegel says many people in Cork are keeping a close eye on water levels, as it could take several hours for rivers to break their banks after heavy rainfall:
Footage from Graignamanagh in Co Kilkenny showed how a street lined with shops was transformed into a fast-flowing river of floodwater.
A number of Stena Line, Irish Ferries and P&O ferry services between Ireland and England have been cancelled due to poor weather conditions. Details of affected services are available on the companies' websites.
Irish Rail also says a number of services have been disrupted this morning.
The ESB says the flow of water through the Parteen Weir is remaining at its current level of 440 cubic metres per second today.
The situation will be reviewed again tomorrow.
— Iarnród Éireann (@IrishRail) December 30, 2015
It is feared the levels in Lough Derg may reach those seen in 2009 in the coming days and, as a result, the flow through Parteen Weir may also increase to 2009 levels in the coming days.
This could lead to more flooding to land and property around the River Shannon downstream of Parteen Weir.
ESB Networks earlier issued an update to say that the rate of flow at the Inniscarra Dam will increase to 250 cubic metres per second at midday today.
Meanwhile the effects of Storm Frank are also being felt in Northern Ireland, Northern England and Scotland.
Winds reached almost 130km/h in parts of the North, and up to 5,000 homes there were without power at one point overnight.
Rain has been falling over already saturated ground, and a swollen river has caused a bridge in Tadcaster in North Yorkshire to partially collapse.