A mountain blaze that raged for four weeks is now "predominantly out", according to firefighters.
The fire broke out at Llantysilio, Denbighshire, on 11 July and at its height had 60 firefighters tackling it.
North Wales Fire Service's Stuart Millington told BBC Radio Wales' Good Morning Wales the fire was now mostly under control.
One crew remains on site to ensure the fire does not "flare up" again, Mr Millington said.
Fires have raged around Wales during the heatwave, including one on Twmbarlwm, Caerphilly county, which caused damage to woodland the size of 250 rugby pitches.
Mr Millington said: "There is still a risk [the Llantysilio fire] is burning underground and could flare up in pockets as it covers a large geographical area."
He said resources are being scaled down during the night, but during the day there is one pump and about 15 firefighters at the site.
Meanwhile, Natural Resources Wales (NRW) is looking at how to restore an area the size of 250 rugby pitches at Twmbarlwm in Cwmcarn Forest after fires over the past three weeks.
Tens of thousands of newly-planted trees were destroyed before excavators, drones, helicopters and tractors were all used to put it out.
NRW's Steve Morgan said the fire had caused "lasting environmental damage", adding: "It is heartbreaking to see so much of the new woodland we have planted at Cwmcarn destroyed."
The site will remain closed as footpaths and bike trails are inspected.
Cerith Griffiths of the fire brigades union said many part-time firefighters had been working full-time around Wales dealing with mountain fires and called their commitment "phenomenal".