About 1500 firefighters are battling more than 70 fires across the state. Up to 30 people have been injured and the number properties lost is expected to rise. Two fires remain at an emergency warning level.

The body of a person was discovered in a vehicle at the Kangawalla fire, near Glen Innes, the Rural Fire Service said on Saturday morning.

NSW Premier Gladys Berejiklian later confirmed a second fatality.

"Our thoughts and prayers of course go to the families and loved ones of those two deceased persons," she said.

A woman who was found unconscious on Friday night with burns to 40 to 50 per cent of her body died in hospital on Saturday morning.

She was found at the Kangawalla Fire near Glen Innes, the same fire near which crews found the body of a person in a burnt-out car.

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NSW Rural Fire Service Commissioner Shane Fitzsimmons said firefighters gave the woman CPR for several hours on Friday night before paramedics could arrive.

"Despite the very best efforts of all involved we are advised this morning that that lady has passed away in hospital as a result of her injuries," he said.

Ms Berejiklian warned the number of fatalities could rise, and said the community must brace itself for worse to come.

"We do need to brace ourselves and what is concerning is that the forecast weather conditions on Tuesday could mean that we're not through the worst of it," she said.

Mr Fitzsimmons said conditions were likely to worsen throughout the day as winds picked up in the afternoon and with no rain forecast throughout the weekend.

He said the blazes had resulted in "significant and widespread damage and destruction" to people, families, home-owners and the wider community with reports of damage to other buildings including a school which was destroyed.

There were 81 fires burning across NSW as of midday Saturday, 43 of which were uncontained, the NSW Rural Fire Service said. Two remain at emergency warning level at Hillville south of Taree and Stockyard Flat near Walcha and 14 at watch and act alert level.

Authorities have appealed to people to register both themselves and any loved ones they are concerned about. The Red Cross says so far 1300 people have registered in eight evacuation centres across the state.

NSW Police has advised the public to delay all non-essential travel in fire-affected areas.

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Mr Fitzsimmons said the blazes they battled on Friday - at one point fighting 99 fires, a record 17 of which were at emergency level all at once - had them in "uncharted territory", with seasoned firefighters of some 60 years experience saying they had never seen such conditions.

"It was unprecedented for New South Wales to have so many fires burdening at the emergency warning alert level," Mr Fitzsimmons said.

RFS Deputy Commissioner Rob Rogers said firefighters had dealt with "horrific" and "traumatic" scenes including helping people suffering with burns and some who had had heart attacks.

He told Nine News multiple blazes raging at the same time on Friday had left firefighters "torn between trying to send help to one fire, to another".

He said dozens of fires are still at risk of affecting properties on Saturday.

In a bleak outlook ahead of expected high temperatures on Tuesday, he said the focus has had to move to preparing for more to come.

"We're never going to get across all these fires before the weather worsens again next Tuesday so our focus is now very much shifting to obviously accounting for what happened yesterday but trying to look forward and keeping going to ensure we can do what we can ahead of the worsening weather on Tuesday," he said.

BOM meteorologist Katarina Kovacevic said while temperatures were cooler on Saturday southerly winds tending southwesterly in the afternoon would gust up to 50km/h.

Conditions were set to worsen early next week, Ms Kovacevic told ABC TV.

Hot temperatures combined with low relative humidity and strong northwesterly winds will increase the fire danger on Tuesday and Wednesday in northern NSW and southeast Queensland.

Firefighters from other states, including South Australia, Victoria, the ACT and the Northern Territory, are assisting crews in NSW.

Prime Minister Scott Morrison says army reservists could be deployed "if necessary".

While they aren't trained firefighters they could help create firebreaks away from the front or provide accommodation and logistical support, he told reporters.

"These fires have already claimed two lives ... and as we get access to further areas that have been cut off we are expecting worse news again," he said.

Mr Morrison said he had been in talks with key cabinet ministers during the morning.

"Our main thoughts and our prayers are with those who have been so directly and horribly impacted by these fires.

"I want them to be assured ... that their governments will be doing everything they can, not just to relieve them from this immediate situation, but to be there in the recovery in the weeks and the months and years ahead."

Glenn Innes Severn Council mayor Carol Sparks said her community had been "badly impacted" with the loss of two people and "many of our houses (and) our school."

"We are so impacted by drought and the lack of rain," she said.

"It's climate change, there's no doubt about it. The whole of the country is going to be affected. We need to take a serious look at our future."

NSW Rural Fire Service building assessment teams are heading to affected areas on Saturday to assess property damage, while crews work to clear fallen trees and reopen roads.

Meanwhile, thousands of people cleared from the path of a bushfire in Noosa in Queensland overnight are in limbo as firefighters assess whether or not it is safe for them to go home.

Tewantin, in Noosa's north, is cut off and there are concerns spot fires could cause more havoc as temperatures rise throughout the day.

Roughly 2000 people were evacuated from parts of Tewantin and Noosa North Shore on Friday afternoon and into the night, independent Noosa MP Sandy Bolton said.

One firefighter broke their leg and a home has been destroyed at Cooroibah.

with AAP