A 4,000-name petition calling for aerial help was prompted by one fire spreading into Coed y Brenin in Gwynedd.
Sian Williams, operations manager for Natural Resources Wales, described the wildfire situation across Wales as "exceptional".
"Unfortunately, despite us putting a request in, at the request of the fire and rescue service... for aerial support, we have not been able to secure that yet," she said.
Williams said NRW Wales had contracts with three operators for helicopter support, but they are already deployed at fires in England and Scotland.
North Wales Fire and Rescue Service said crews were continuing to deal with a wildfire at Capelulo near Sychnant Pass, in the wake of a large grass fire on Conwy Mountain.
There is also a multi-agency response following a blaze on Rhinogydd mountains in Gwynedd, where householders have been advised to keep windows and doors closed.
Elsewhere, firefighters are dealing with grass fires at Hope Mountain and Brymbo in Wrexham county, Pentrefelin, Holyhead, and Pentre Halkyn, overlooking the A55 in Flintshire.
Ecologist Angharad Owen, who started the petition calling for aerial support to tackle blazes in remote places like Rhinogydd, said they were "proven to be highly effective in managing and extinguishing wildfires swiftly".
"These resources can access remote and rugged terrains, dropping water and fire retardant directly on the fire's critical areas, something that ground forces might struggle with in vast and challenging landscapes like Rhinogydd," she said.
"It is devastating to see our natural environment being harmed by this wildfire.
"Not only is this impacting our vital ecosystems and the wildlife that calls it home, but it is also posing serious risks to human health and safety."
Caroline Mason, from Rhiw Goch Inn campsite at Trawsfynydd, said she went to bed on Sunday night "seeing the mountain literally ablaze".
"I could hear the sounds of the fire burning. It woke me up," she said.
"I was so worried and distressed that the fire was not stopping .Instead, it was growing with momentum, and it was moving closer this way."
In south Wales, firefighters have been tackling a wildfire at Blaenavon in Torfaen county for the third day, with smoke affecting communities across a wider part of the region.
Residents said the smoke from the Blaenavon fire had caused a "fogginess" and "acrid smell" stretching for several miles between Torfaen and Pontypool.
"You just need to keep your washing to a minimum and shut all your windows and doors," said Alison Probert.
