Three deaths have already been confirmed in the fires - including 69-year-old Wytaliba resident Vivian Chaplain, and another man identified as George Nole - and there are fears the death toll will rise.

On Sunday, fire assessment teams were tallying property damage from volatile bushfires that ripped through large chunks of NSW over two days.

While weather conditions have eased, 72 bushfires continued to burn across NSW on Sunday morning with 36 still not under control, while a further 11 fires were at watch and act levels.

The NSW Rural Fire Service issued a stark warning on Sunday ahead of "dangerous" conditions on Tuesday and urged residents to "get ready now" as the fires would not be contained in time.

"These conditions will be as bad, if not worse, than those experienced on Friday as they will be across a much broader area including large population centres like Sydney," the NSW Rural Fire Service said.

"Under these conditions, these fires will spread quickly and will threaten homes and lives."

The fire danger ratings of "severe and extreme" are expected to cover a much broader swath of NSW on Tuesday, extending from the northern parts of the state, to potentially across the Central West, and the greater Sydney and Illawarra region, to the South Coast.

NSW Rural Fire Service Commissioner Shane Fitzsimmons said assessment teams were bracing themselves for "considerable losses".

"There are communities and fire grounds where we are expecting to tally up considerable losses of homes and other properties," Mr Fitzsimmons said on Saturday.

"A number of our own fire stations have been destroyed."

At least 150 homes have been destroyed by the fires and a school at Glen Innes was severely damaged, although this number is likely to climb as detailed assessments begin.

Mr Fitzsimmons said other important community assets had also been lost in the fires.

"We're talking about schools being destroyed, we're talking about community halls, bridges, power poles," he said.

"All of those sorts of things - they get consumed in the path of a volatile fast-moving fire."

Fire assessment teams would comb through devastated areas over the coming days, Mr Fitzsimmons said.

"Clearly, from what we are seeing, and we do not have indicative assessments from all these fire grounds yet, but estimates are at least 150."

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The rural fire service would also be coordinating relief work with the Australian Defence Force.

Relatives paid tribute to Ms Chaplain, who is believed to have died while defending her home at Wytaliba, north-west of Coffs Harbour.

Her daughter-in-law Chrystal Harwood said Ms Chaplain would be "greatly missed" by her two children and six grandchildren as she described her desperate attempts to reach her by phone after the line went dead.

"She was in an absolute panic. She said, 'We're on fire, there's fire everywhere, I need the boys here now,' " Ms Harwood told Nine. "And before I got to tell her to just get out, she'd hung up on me and I couldn't get back through to her. I tried so many times."

Ms Chaplain was found unconscious with burns to 40 to 50 per cent of her body at the Kangawalla Fire near Glen Innes in north-eastern NSW. She was taken to hospital where she died.

The body of George Nole was also found at Glen Innes in a burnt-out car on Saturday morning.

Another body was found in a burnt-out building in the township of Johns River, north of Taree, on Saturday afternoon.

Bobin residents Margaret and David Thies were trying to save a neighbours' home when flames from another direction quickly overcame their property.

With fire already engulfing their shed, the elderly couple only had time to grab their dogs and some cash before fleeing to a safe house with other people who had lost their houses, their grandchild Shani Nixon said.

"They all stayed awake in turns just staying alert for more danger," she said.

"We didn't hear from them in over 24 hours, it was such a horrible night not knowing and listening to the RFS scanner."

A team of volunteer firefighters from the Tasmanian Fire Service are scheduled to arrive in NSW to help local firefighters battle the blazes.

NSW Premier Gladys Berejiklian warned that the worst of the "unprecedented fire conditions" may not be over as firefighters face similar conditions on Tuesday.

"We are seeing a situation in NSW with these fires we have not seen before," she said.

The Rural Fire Service's Commissioner Fitzsimmons said it was unprecedented for NSW to "have so many fires" burning at the emergency alert level.

"It is a sobering reminder of what's around the corner," he said.

While firefighters will try to secure as many fires as possible over the next few days, Mr Fitzsimmons said the reality was that they would "simply not be able to contain these fires".

The forecast for the rest of the fire season is driven by above average temperatures and below average rainfall, which have been exacerbated by the state's severe drought.

Mr Fitzsimmons said fires were starting extremely quickly, "spreading and burning very intensely, very aggressively", while spot-fire activity was double or triple that which was usually expected.

"We have got the worst of the fire season ahead of us - we are not even in summer yet," he said.

So far this bushfire season, NSW has had 6000 fires and the area burnt is already nearly three times the entire amount of land scorched across the state during the last season.

The federal government is considering deploying Australian Defence Force personnel, including reservists, to help on fire breaks and logistics, although it cautioned that they were not trained firefighters. The ADF is already providing airlift support, including C-130 Hercules aircraft.

Prime Minister Scott Morrison said on Saturday he wanted to assure those in the communities ravaged by fire, or those facing a fire threat in the future, that there was a "high level of co-ordination of response" across the state and Commonwealth governments.

"The fires themselves will continue to present a risk for some weeks to come. With changing weather conditions, they could flare up in the future," he said on Saturday morning.

"Sadly, we have lost two Australians and I fear that we will lose more before the day is out."

Mr Morrison said Australia always had to brace itself for the fire season, side-stepping questions about whether those ravaging NSW were in some way linked to climate change.

Asked whether he accepts that what NSW is experiencing is in some way linked to climate change, he said: "My only thoughts of the day are with those who have lost their lives and their families, firefighters who are fighting the fires, the response effort that has to be delivered and how the Commonwealth has to respond and support those efforts."