CFB Petawawa Fire Chief Barry Nagora said at a news briefing Monday afternoon that "in layman's terms, the fire is out."
Nagora said the blaze, which spread to 210 hectares over the weekend, was likely caused by lightning.
Parks Ontario spokesman John Swick said while the assessment is the base's to make, there are still concerns over embers deep in the soil in the area.
Swick said until those hotspots are dealt with, the Restricted Fire Zone Order in Algonquin and the closure of the entrance to the park at Barron Canyon Road would remain in effect.
No training exercises at time of fire
The fire was first spotted at about 2 p.m. ET Thursday on military training grounds near a firing range, and quickly grew in hot and dry conditions. The fire prompted Algonquin Park to issue an evacuation notice to campers in the eastern portion of the park.
Nagora said there were no exercises and no soldiers present in the area where fire broke out.
Fire investigators are looking at meteorological records at the base, including lightning strike data, to confirm the cause.
A thunderstorm moved through the region Monday afternoon, dropping rain on the area for about 20 minutes while Nagora briefed media about the status of the fire.
Nagora said a second five-hectare fire is burning in a swamp about 14 kilometres from the original fire site, but said it poses no threat to the base, Algonquin Park or the town of Petawawa, Ont.