The NSW Rural Fire Service confirmed reports properties had been lost but were not able to say the exact number or location as field assessment teams were yet to arrive to undertake a review.
There were no reports of missing people.
Crews were provided some relief when a cool southerly change moved across the fireground in the early hours of Wednesday morning.
While the fire near the popular holiday town of Bermagui and the neighbouring Cuttagee and Barragga Bay is still burning, the threat warning has been downgraded to watch and act.
But Commissioner Rob Rogers urged residents not to be complacent as fire danger remained and to stay informed about the RFS alerts.
"We know properties were lost, we just don't know how many and that work will obviously go on this morning," he told Nine's Today Show on Wednesday.
"The good news is there are no reports at the moment of anyone missing, which is good to hear, but we've got to confirm that everybody is okay in those areas because there's a lot of scattered properties firefighters were struggling to get in to."
The south coast fire is still more than 5000ha in size and continues to burn near homes in the Cuttagee, Barragga Bay, Murrah, Bunga and Goalen Head areas.
"Firefighters are working in the area to slow the spread of the fire," the RFS said.
The southerly change that moved through the fireground overnight has brought cooler temperatures, increased humidity and some rain.
Evacuation centres in Bega and Narooma remain in place.
Conditions have also improved in other parts of NSW after fire crews battled around 80 bushfires on Tuesday.
For Wednesday, three total fire bans are in effect in the Greater Hunter and further inland in the Northern Slopes and North West areas where the fire danger ratings range from high to extreme.
"Warm to hot and dry with fresh and gusty northerly winds expected during Wednesday," the Bureau of Meteorology said.
On Tuesday, temperatures reached 37.2C at Sydney Airport with the city centre, Penrith, Gosford and Nowra all cracking 35C.
The temperatures are as much as 15C above the October average maximum for the same locations.
Wednesday is unlikely to measure those highs, with temperatures forecast in the high 20s for greater Sydney.
This bushfire season is expected to be the worst in NSW since the Black Summer of 2019-20.
Premier Chris Minns said forecasts of a "horrific" bushfire season was one of the things that kept him up at night.
"I don't want anybody to get over-confident - this could be a really tough bushfire season," he said on Tuesday.
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