A Red Weather Alert has been issued for the whole country as Hurricane force winds are expected in every county.The National Emergency Coordination Group has advised people to stay at home, and no unnecessary travel or other outdoor activities should be undertaken.
They said that all schools, colleges and childcare facilities will be closed.
They have also advised people to secure any garden furniture, bins and other outdoor equipment before the storm hits.
The decision was taken following a special meeting of the government task force on emergency planning.Irish Defence Forces are on standby to deploy resources, including transport and engineering assets.
Ophelia is the most powerful Atlantic storm this far east on record packing "violent, destructive" gusts of over 130 kilometres per hour.
Heavy rain, storm surges and flooding are likely in coastal areas - and the entire country has been placed on the highest state of alert.
The Department of Education and Skills has publicly informed all schools, colleges and other education institutions that they are to remain closed.
The HSE has said all hospital outpatient appointments are being cancelled. Patients do not need to attend or contact their hospital and they will be rescheduled as soon as possible
Bus Éireann has cancelled all services nationwide from 5am to 2pm due to the national Status Red weather alert and airlines have advised intending passengers to check the status of their flight before travelling to the airport.
Dublin Airport and Shannon Airport have advised passengers to check the latest flight information before travelling to the airport.
Cork Airport said cancellations are likely, adding: "We ask all passengers to check flight status with their airline & to avoid travelling to @CorkAirport on Mon unless absolutely necessary."
Responding to passengers' questions, Aer Lingus said it is monitoring the situation closely and that so far no changes have been made to its schedule.
Ryanair said: "We will inform customers in the event of any changes to our flight schedule and the latest flight information will be posted on the Ryanair.com website."
Dublin Bus has said that they expect to operate morning peak services as normal, but here will be significant disruption to services between 9am and 6pm.
This may include no services being available during this time.
However, customers should be aware that services may experience delays and disruptions to service and service levels will be dependent on weather conditions.
The transport company said they will update their website, www.dublinbus.ie, regularly.
Customers can also get updates on their Twitter account; @dublinbusnews or call our customer service line on (01) 8734222.Irish Rail have cancelled some services due to the storm.
All DART, Intercity and Commuter services are operating this morning EXCEPT on the following routes:
Limerick Junction to Waterford
Limerick to Ballybrophy via Nenagh
A speed restriction of 80kph (50mph) will be in place on the following routes:
Tralee to Mallow
Cork to Charleville
Cork to Cobh/Midleton
Waterford to Kilkenny
Rosslare Europort to Gorey
Delays of 15 to 30 minutes are expected to services operating on the following routes for morning services:
Cork to Dublin
Tralee to Cork/Dublin
Waterford to Dublin
Rosslare Europort to Dublin
Separately, a signal fault between Galway and Athenry, unrelated to the storm, is causing delays of up to 45 minutes to services to and from Galway.Constant Updates on https://twitter.com/sligotoday