Scottish airports on the West Coast, including Glasgow Airport, have been hit by fresh warnings of volcanic ash.
The Civil Aviation Authority, that regulates UK airspace, advises today that airports in Glasgow, Prestwick, Inverness, Stornoway, Benbecula, Tiree, Islay, Barra, and Campbeltown are likely to be closed from 07:00 until 19:00 local time.
Northern Ireland has also been affected with airports closed at Belfast International, Belfast City, and Derry.
The CAA adds in its 2am advisory that Edinburgh Airport remains open.
"Current forecasts show that the 60 nautical mile buffer zone imposed around high concentrations of ash may be close to the following airports: Edinburgh, Carlisle, Blackpool, Liverpool, Manchester," the aviation authority says on its web site.
It adds: "However, based on current forecasts CAA has assessed that these airports can safely remain open, but passengers should check with their airline before travelling to the airport, as the situation is dynamic."
Some airlines, such as British Airways, have cancelled Edinburgh airport flights as well, as a precautionary measure.
BA says on its web site: "Due to levels of volcanic ash over Scotland today (Wednesday), we are cancelling all flights to and from Glasgow, Aberdeen and Edinburgh until 1pm".
Passengers travelling to and from Scotland should check with their airline to see if their flight is affected.
The CAA says it does not expect airports in the South East of England to be affected.