Firefighters battling the North Black Range fire near Braidwood are preparing for another difficult day on Friday, although conditions have eased slightly on the ground.
The fire, which has burnt more than 31,000 hectares and is spreading in multiple directions, was downgraded overnight from an emergency warning level to advice.
The Kings Highway was closed north of Braidwood, between Columbo Road and Mayfield Road, at about 4.30pm on Friday.
Fire activity on the north-eastern edge of the fire caused the road closure with heavy smoke affecting visibility.
Motorists were advised to stay away with no suitable diversions in place.
Strong winds made conditions on the ground difficult on Thursday, when the fire shot into the air above trees.
Queanbeyan fire patrol centre spokesman Daniel Osborne said a difficult day was ahead.
"We're not expecting Friday to be as bad as Thursday but there's the potential for it to be another challenging day for our firefighters," he said.
"We expect the fire activity to increase throughout the day, driven by winds, low humidity and drought conditions."
The fire is continuing to burn in a north-east direction towards the Kings Highway. It's also spreading to the south-east and crossed Cooma Road into the Elrington area.
The fire to the south of Cooma Road has been contained but continues to burn on the northern side of the road.
Increased fire activity throughout the day is expected to put pressure on containment lines and in areas north east of Colombo Road, Larbert Road and the Kings Highway and to the south of the Tallaganda Forest.
The fire forced the closure of the highway to drivers for several hours on Thursday.
As of 12.30pm on Friday, the Kings Highway was closed west of Braidwood between Columbo Road and Mayfield Road in both directions.
No suitable diversions are in place.
Araluen Road has been closed to drivers between Braidwood and Moruya.
Traffic authorities say residents may be allowed access at the discretion of emergency services.
Parts of the highway east of Braidwood between Monga and Nelligen have also been closed to allow for backburning for the nearby Currowan fire on the South Coast.
Traffic authorities say smoke in the area may affect visibility and urged motorists to drive to the conditions.
One caravan was lost during Thursday while one home and several outbuildings were destroyed over the weekend.
A total fire ban has been declared in the Southern Ranges area for Friday with the fire danger rating at very high.
Westerly winds will continue to hit the fireground throughout Friday although they aren't expected to be as strong as those seen on Thursday.
Winds of between 30 and 50 kilometres per hour are forecast for the area.
"We don't expect the fire to move as far as it did on Thursday but it has the potential for it to move," Mr Osborne said.
Crews monitoring the North Black Range fire are also monitoring the Currowan fire on the South Coast as it moves westward into the Budawang National Park near Mongarlowe.
While fire modelling doesn't show the Currowan fire linking up with the North Black Range fire, Mr Osborne said the fire had moved into the Queanbeyan-Palerang area.
"We're planning to do backburning there later on Friday evening."
An evacuation centre for affected residents will open from 1pm at the National Theatre in Braidwood.