Sustainable Timber Tasmania sector commander Aaron Foley has participated in 12 seasons of firefighting.
He said comparable to previous blazes, the fires burning at Fingal were "pretty hectic".
There is a large fire burning on either side of the town of Fingal, one about 5000 hectares to the south and the other about 10,000 hectares to the north.
Cooler weather conditions on Sunday allowed the TFS, STT and other emergency services to undertake containment efforts: using 32 fire trucks, 99 personnel, seven aircraft and machinery.
"It's the terrain - a lot of it is inaccessible, and the topography, the rock, changes the weather patterns," Mr Foley said. "So a lot of the weather we're getting up here isn't what the forecast necessarily predicts, so it's very difficult to operate. The wind can whip up pretty quickly as well."
The area has experienced its driest three-year period on record.
"We've got fire in front of us and fire behind us and this little strip in the middle, which is a tinderbox waiting to go off," Mr Foley said.
Emergency services spent Sunday with one priority being keeping the fire away from an exposed coal seam left over from a former mine, burning in close proximity to the blaze.
The rehabilitated mine closed about seven years ago but some coal was left exposed.
Bulldozers and machinery were used to cover the exposed coal on Sunday, so that it wouldn't combust in the event of the fire passing through.
Mr Foley said fire that got into a coal seam would continue burning indefinitely.
"It happened over at the Scamander fires in 2006-07," he said. "It's still burning, to my knowledge."
There are also other Duncan Colliery mine infrastructure and assets in the fire region that services are working to protect.
The other major risk is that the fire could spread into Douglas-Apsley National Park and through to communities on the East Coast, an event the containment activities are aiming to prevent.
A spike in dangerous fire conditions is expected on Thursday.
Mr Foley said STT's losses would be assessed after the firefighting was finished.
"None of it's a five minute job, it's not as straightforward as anyone would like," he said.
Meanwhile, a fire at Flinders Island has burned 2738 hectares but was not at any alert level as of Sunday.