Around 30 campers remained stranded near Moruya on Wednesday night, due to flooding caused by the storm that swamped the NSW south coast earlier in the week.
State Emergency Services became aware of the campers stuck in a remote stretch of the Deua National Park on Tuesday night.
They were able to make contact 24 hours later, but could not cross a waterway to reach them, Illawarra-South Coast SES incident controller Ashley Sullivan said.
It is feared they could remain isolated for up to five more days.
Five children are believed to be among the group stuck in the flooded Bendethera area.
"We were able to establish radio communications with the campers on the other side of the river, and at this stage we have about thirty odd people out there, which is more than we thought this morning," Mr Sullivan said.
"We have grabbed all of their personal details, and intel back is that everyone is okay at this stage and that no one is in any life-threatening situations."
He believes none of the campers have run out of essential supplies, although is concerned they could be running thin.
Crews will try to reach the campers by ground and air on Thursday morning, as the floodwaters cutting off access to and from the national park are unlikely to reduce overnight.
"Hopefully the helicopter is favourable tomorrow and we can get access to them and have a chat face-to-face and potentially drop off additional supplies," Mr Sullivan said.
"But these campers could potentially be stranded for a further two to five days, some of them even longer."
It is understood the group of families was supposed to return several days ago, but was forced to extend the stay due to the wide-ranging floods.
There are three different major camp grounds the families could be isolated at and crews will attempt to reach all of them on Thursday to search for more campers affected by the floods.
"If people are concerned about their friends and family, don't wait, let us know while we still have resources active in the area," Mr Sullivan said.
Widespread flooding, a landslide and a helicopter search were among the havoc that took place across the NSW South Coast on Monday and Tuesday, but the wet weather has eased since.
Mountain ranges sheltered Canberra from the worst of the heavy rain. The scattering showers it had seen throughout the week were tipped to stop by Thursday.
Bureau of Meteorology forecaster Andrew Haigh said temperatures in the capital will warm up across the weekend.
"It will be partly cloudy or mostly sunny for the next few days, with a possible shower returning Monday," he said.
"Thirty one on Saturday, 32 on Sunday and possible shower and 34 on Monday."