A CAA spokesman said: “Met Office forecasts show that levels of ash in the atmosphere over Scotland and Northern Ireland will exceed the concentrations that engine manufacturers have agreed are safe for operations.
“Unfortunately, this means that the CAA anticipates all Scottish and Northern Ireland airports will be closed from 7am local time tomorrow.
“The forecasts also show that it is likely that the ash cloud will continue to move south, potentially affecting airports in the north-west of England and north Wales tomorrow,” he said.
RTÉ notes that the IAA is to review the situation for Irish airspace, and airlines, overnight.
Adds The Guardian are live-blogging the situation
And RTÉ notes that Dublin airport is closed until midnight
Shannon Airport will close from 5.30pm until midnight, while Cork and Kerry airports will be open until midnight. Waterford Airport will be open until at least 7pm.
Northern Ireland’s two main airports, Belfast International at Aldergrove and the George Best Belfast City Airport, are both remaining open until 1pm.
The situation there is described as ‘fluid’ and some flights are arriving and departing. At the moment, they are scheduled to close from 1pm to 7pm.
Scottish airspace is also affected. Glasgow Airport is closed and Edinburgh Airport is to shut from 1pm until 6pm.
Update No-fly zone time extended. From the BBC report
Earlier, the Civil Aviation Authority at 1300 BST had announced it would be in place until 0100 BST.
However, the National Air Traffic Services has now said the zone would remain until 0700 BST [Thursday].
It added: “Latest Met Office information suggests the cloud will move west overnight.
“Based on this information, we expect most of the airfields listed above to become available again from 0700 BST.
“However, we would caution that the ash cloud is dynamic and continues to change shape and the situation may change again.”