The North Black Range fire has breached containment lines in Tallaganda State Forest and forced firefighters to withdraw to Mulloon Road.
Firefighters are dealing with spot fires and erratic wind is making the situation challenging, NSW Rural Fire Service Inspector Chris Allen said at 2.30pm.
The fire has burnt 1100 hectares in Tallaganda State Forest since Tuesday.
There is currently no threat to properties but it's unlikely the fire will be contained before Monday, Inspector Allen said.
Back burning will be undertaken to try to contain the fire, which will lead to an increase in smoke on Friday and the weekend, Inspector Allen said.
"An easterly wind is forecast for later today and this will push smoke towards Queanbeyan. Freshening north-westerly winds will resume on Friday," he said.
NSW Parks and Wildlife and NSW RFS crews are supported by helicopters and bulldozers.
The fire is burning through dense bush in an isolated and hard to reach area, Inspector Allen said.
"Despite the significant smoke visible in the surrounding area, the fire is moving relatively slowly thanks to the terrain and weather conditions over the last two days," he said.
People, particularly those living in the area around the park, should maintain an awareness through:
- The "Fires Near Me' app;
- The NSW Rural Fire Service or NSW Rural Fire Service Lake George Zone Facebook Pages; or
- Local media.