The Orroral Valley bushfire, which has been burning in the Namadgi National Park for almost a month, has been downgraded to patrol status after days of heavy rain.
The ACT Emergency Services Agency said a major re-ignition of the fire was unlikely following the downpour.
"The fire is at a stage where firefighting resources are only required for patrol purposes," a spokesman said.
As of Monday afternoon, there were 40 hot spots still burning across the fireground, mostly in highland areas, down from 200 hot spots 10 days before.
The fire will be declared officially extinguished once no hot spots have been detected on the fireground for 24 hours.
ACT Emergency Services Agency commissioner Georgeina Whelan said crews were allowing the fire to burn itself out.
"We received 60 millimetres across the fireground over the weekend, which assisted in firefighting efforts," she said.
"It's ensured that the fire situation is nowhere near as bad as it was.
"Containment lines in the south and western areas of the fireground have proved invaluable."
Aerial surveillance will be carried out over the fireground on a daily basis to detect hot spots.
The fire started on January 27 in the Namadgi National Park and was sparked by a landing light on a defence helicopter.
The blaze has burnt more than 86,000 hectares, or more than one-third of the ACT land mass.
The fire threatened many homes in the village of Tharwa to Canberra's south and suburban areas of southern Tuggeranong.
Multiple spot fires from the Orroral Valley blaze crossed over into NSW and destroyed several properties in the Bumbalong Valley.
ACT conservator of flora and fauna, Ian Walker, said crews were assessing areas of Namadgi National Park for damage.
He said assessing burnt out trees would be a key focus going forward to ensure safety for visitors once the park reopens.
"There's a lot of environmental resilience," he said.
"We need to allow nature to take its course. We may have to do this over many years."
Mr Walker said getting visitors back to Namadgi was a priority in the months ahead.
More than 80 per cent of the national park had been damaged in the fire.
"We'll make a decision [to when to reopen the national park] in coming weeks," he said.
"The first stage will be working with the Ngunnawal community to bring them back on country ... and provide an opportunity to the rest of Canberra so they can enjoy what Namadgi has to offer."
Mr Walker said while ash and debris had been seen in nearby waterways in recent days, it was something regularly seen in the aftermath of fires and drinking water would not be affected.
Firefighting efforts were boosted thanks to heavy rainfall across the ACT earlier this month.
In the 24 hours to 9am on February 10, the ACT received more than 60 millimetres of rain.
That amount represented Canberra's mean rainfall for the month of February in just one day.
Frequent showers throughout the week had led to easing conditions across the fireground.
The national park remains closed to the public, but some signs of life have returned to the area following the devastation of the bushfire.
Experts said green shoots were on their way, and animals had been seen in bushland.