A WEEK of major travel uncertainty lies ahead for thousands of air passengers with the return of the volcanic ash cloud.
At Dublin Airport 36,000 travellers were caught in the chaos last night and this morning. The airport was due to reopen this afternoon.
Most other airports in the country were operating normally.
Thousands of travellers have been affected by the sudden closure -- although North Atlantic flights through Irish airspace have not been affected.
Cork, Shannon and Kerry airports will all remain open as normal, while Waterford and Galway airports reopened at 6am this morning and Sligo and Ireland West Knock were due to reopen at 9am.
Donegal airport was also closed until midday at least.
Dublin has been the worst affected, with almost 300 flights cancelled last night and this morning, hitting about 36,000 passengers.
The decision to close came after the IAA carried out observational flights at various different altitudes to determine the safety of travel in Irish airspace.
Dublin Airport Authority spokesperson said that passengers should not travel directly to the airport, but instead contact the airline on which they were due to travel.
Ryanair, Aer Lingus and Flybe warned passengers to check their airline's website for fresh updates.
Those with flight reservations whose flights have not been cancelled are being told to go to the airport as normal.
Delays are expected as airlines are expected to reposition crew members and aircrafts, as well as the fact that not all aircrafts will be in place.
Met Eireann has said that a southwesterly airflow is expected today and it is predicted that the ash cloud will gradually be pushed away towards the northeast.
A spokesperson said: "The mainly southwesterly airflow will persist through the rest of the week and should keep the ash away from Irish airspace."
As travel disruptions have continued several weeks after the Icelandic volcano Eyjafjallajokul initially erupted, scientists have admitted that there is no indication that the disruptions will end anytime soon.
Minister for Foreign Affairs Micheal Martin was one of those hit by the travel disruption and was unable to travel over the weekend.
He had been due to meet new British foreign secretary William Hague today but was forced to re-schedule his trip.