Milder temperatures on Christmas Day and Boxing Day have provided weary fire crews with a welcome respite from last week's catastrophic conditions in which around 100 homes were destroyed and two firefighters died.

"What we have seen today is a general easing in fire conditions and we expect that to continue tomorrow," a NSW Rural Fire Service spokesman said on Christmas Day. "That gives us the chance to establish or strengthen containment lines."

There were still 74 bush and grass fires burning across the state late afternoon on Christmas Day, including almost 30 yet to be contained. All were advice level, reflecting the milder conditions.

Among the blazes still out of control is the large Currowan fire south-east of Canberra, which has burnt through more than 231,000 hectares between Batemans Bay and Sussex Inlet, while the adjacent Charleys Forest fire east of Braidwood, which is more than 32,000 hectares in size, was being brought under control.

The fires have forced the closure of Kings Highway south-east of Braidwood, forcing holidaymakers and other travelling to and from the South Coast to make lengthy detours either on the Snowy Mountains Highway through Cooma and Bega or the Illawarra Highway.

Meanwhile, the massive Gospers Mountain fire, which has burnt through almost 500,000 hectares of Wollemi National Park, remains out of control, and Sydney remain ringed by 11 blazes, five of which were listed as out of control.

NSW remains under a seven-day state of emergency declared by Premier Gladys Berejiklian last Thursday, empowering the RFS Commissioner to order evacuations, close roads, enter or seize properties, order the shutdown of essential services like electricity and gas, and direct and control government agencies and resources.

The declaration will come up for review today.

According to the RFS's latest impact assessment, issued on Christmas Eve, almost 1000 homes have been destroyed since the fire season began on July 1, as well as more than 2000 outbuildings and 68 facilities.

The service said a further 7824 homes, 7053 outbuildings and 615 facilities had been saved as a result of the effort of fire crews.

The RFS spokesman said more than 2000 volunteers and crews were working on fire containment lines on Christmas Day as part of preparations for a heatwave expected to send temperatures soaring from Friday through to New Year's Day.

He said the firefighters were being rotated during the day in order to allow them to spend time with their families, and special meals were being provided.

The RFS said it had been overwhelmed by community support, including the donation of a huge amount of goods.

But the service said that it had received so much that in many places "we have little room [left] to hold these supplies". It has asked people to instead donate funds.

"What [communities] told us they need most right now is ... money."