The state reported 36 fires on Thursday evening, down from more than 90 blazes two days earlier.

On the most significant fireground, on the NSW far south coast, fire crews were buoyed by at least 20mm of rainfall and were able to strengthen containment lines and mop up on Thursday.

Aircraft and heavy machinery continued to operate throughout the day as hotspots continued to burn in Barragga Bay and neighbouring towns.

While cooler conditions were expected to remain for several days, the Rural Fire Service warned of an increased risk of falling trees and pockets of active fire remained in parts of the fireground spanning 6800 hectares.

Disaster assistance was announced to help affected Bega Valley residents pick up the pieces, under Commonwealth-state recovery funding arrangements.

Emergency Services Minister Jihad Dib said the assistance would support communities, landowners, farmers and primary producers in the clean-up and recovery after the bushfires.

Meanwhile, more than $40,000 was raised within a day for a young farming family affected by bushfire for the second time in four years.

The family said they were at breaking point after Tuesday's inferno began in a neighbouring Coolagolite property and swept over their dairy farm, one of several properties also hit in the Black Summer fires of 2019-20.

It came as building assessment crews backtracked on a count of four homes being destroyed, confirming two were destroyed but two suffered less damage.

Nineteen sheds were either destroyed or damaged while 105 structures were unaffected as the fire tore through national park and entered beach communities.

After several busy days, the Rural Fire Service is expecting the north western region, surrounding Narrabri, to be the only site of a high fire danger rating this weekend.

Still, Premier Chris Minns warned of a "horror summer" given the far south coast blaze began in an area already affected by the 2019/20 fires.

"It means there's a significant load that's regrown enough to have a bushfire go through it and that's a concern for the Rural Fire Service and for those communities," he said.

Meanwhile, high winds and heavy rainfall kept SES volunteers busy across the state with roofs blown off in the state's north and sandbagging needed closer to the Victorian border amid riverine flooding.

More than 290 calls came in within 24 hours but the SES praised the public for heeding safety warnings, with no reports of injuries or rescues.

Strong winds also caused havoc at Sydney Airport, which was forced to switch to a single runway and cancel more than 100 flights.

Australian Associated Press