Thousands of acres of forest, moorland and wildlife in Co Galway are at "major risk of destruction" because of a gorse fire, according to Coillte.
A fire service is battling the fire at Cloosh Valley, which escalated out of control this afternoon.
It said that Galway Wind Park, Ireland's largest wind farm, is located within the forest and is at close proximity to the fire.
The fire is described as being "out of control" and rough terrain and high winds are making the operation to contain the blaze more difficult.
It is hoped that when temperatures drop as night falls the fire may subside a little.
There is a plan to fight the fire using two helicopters tomorrow morning.
Gerard Murphy, Managing Director of Coillte Forest, said: "The recent outbreak of fires, particularly across the west and north of the country, has been responsible for the worst damage to Coillte's estate since 2011.
"The combined loss of productive timber, together with the cost of replanting the affected areas, will result in a multimillion euro bill.
"In addition to the damage caused to commercial forestry, these forest fires pose a significant risk to farmland, native woodland and areas designated for nature conservation."
The Cloosh Valley forest is the biggest in Ireland; it is around 4,000 hectares and around a quarter has already been lost to the fire.
Gorse fire leaves Mayo family homeless
A family in Co Mayo has been left homeless after a gorse fire destroyed their house over the weekend.
Fires around Kiltimagh have destroyed hundreds of acres of forestry and bog in recent days.
While the fires have now been put out, there are concerns that hot weather or human interference could reignite them over the coming days.
The Brennan family home went ablaze when embers from a gorse fire lodged on the thatched roof of the five-bedroom house.
Efforts to contain the spread by locals and several units of Mayo Fire Service were in vain. The property was gutted and the family escaped with just a few possessions.
Gorse fire destroys house in Co. Mayo. More on @rtenews pic.twitter.com/NXXvHjpYfe
— Pat McGrath (@patmcgrath) May 8, 2017
It is thought the fire started around 1.6km from the house and spread rapidly. Strong winds increased the pace of the blaze.
Bernice Brennan spoke of how she was left helpless as the fire took hold. She has paid tribute to the local community for their assistance since the blaze.
Gorse fire leaves Mayo family homeless https://t.co/s4XyBxtISb pic.twitter.com/hUpcfGL48G
— RTÉ News (@rtenews) May 8, 2017
Fire crews managed to salvage a dress for Mrs Brennan's daughter from the house, ahead of her first communion celebrations on Saturday.
Farming organisations and fire service personnel have appealed to people to be mindful of the risks gorse fires can bring.
In particular, they are urging that extreme care is taken when disposing of matches or cigarette ends at all times.
