Met Éireann has issued a Status Red weather warning for Dublin, Kildare, Louth, Meath, and Wicklow.
It issued its highest alert from 5am this morning after heavy overnight snowfall led to accumulations of 5-10cm in the east of the country. Some reports suggest the accumulations could reach 25cm over the coming days.
The Red alert will continue until 12 noon tomorrow, Thursday 1 March.
A Status Orange Snow-ice Warning is also in effect for Carlow and Laois. A Status Yellow Snow-ice warning is also in place for counties Kilkenny, Longford, Wexford, Offaly, Westmeath, Cork, Tipperary and Waterford.
Further snow is forecast throughout the day with the heaviest and most frequent showers in the east.
However, snow is also expected to reach the midlands and southern areas as storm Emma approaches.Gardai say it is a fluid situation and motorways are open but some problems are occurring on slip-roads entering and exiting motorways, with trucks in particular finding it difficult.
Public transport could be affected by the adverse conditions and commuters are advised to check the online status of their travel plans before leaving home.
InterCity trains, including the Sligo - Dublin service, are all currently operating as normal.
Ianród Éireann says services are operating on all services, except Cobh to Cork, while the DART is also running but there are some delays on both services. Irish Ferries fast craft sailings on Dublin to Holyhead route have been cancelled.
Dublin Bus said that there will be significant disruption to services this morning, with services only operating on main corridors due to the poor road conditions.
There are disruptions to Luas where a limited service in now operating.
PSO and Expressway services in the east seriously affected.Flights cancelled
It said it is reviewing the situation on an ongoing basis and is taking advice from Met Éireann and the National Emergency Coordination Committee.
Decisions as to whether it is necessary to close schools will be made locally by boards of management.
Dublin Airport said a number of flights have been cancelled. It asked people to check with their airline for latest flight updates before coming to the airport.
The National Emergency Coordination Committee is due to meet again this morning to discuss the deteriorating weather.
The Courts Service has said that Court houses in Dublin and other Red Alert counties will not be opening today. Continued Red Alert counties will also see court facilities not open on Thursday or Friday.