Volunteer firefighter Neville Smith, 66, was left in a critical condition after suffering serious burns to his face, arms, back, hands and airways while fighting a fire at Tenterfield on Saturday. A fire truck was also destroyed in the blaze.

"He remains in the intensive care unit and is likely to be in the intensive care unit for some time," RFS chief Shane Fitzsimmons said.

Mr Fitzsimmons said firefighters were now working to protect Mr Smith's home, which is also under threat in the area.

"Our focus right now is on the security of his home and the welfare of his animals, and of course, he is in the hands of the best medical care that we can afford," he said.

"He is a recipient of the Rural Fire Service 10 year long service medal ... he loved his work in the Rural Fire Service."

Fires also hit Sydney on Saturday afternoon, with a 'Watch and Act' level fire currently burning in South Maroota in the Hills region. Firefighters are on scene trying to slow the spread of the grass and bush fire, with more crews currently being sent out.

Mr Fitzimmons said the "extreme" conditions were a "sobering reminder" of what is ahead, stating that it was "very unusual" to see these sorts of fires this early in the season.

"Never before have we recorded extreme fire danger conditions this early in the month of September," he said. "Normally you would expect those sorts of conditions as you come closer into the summer months."

Two fires in northern NSW at Tenterfield and Ebor remain at 'Emergency Warning' level, with residents in Ewingar, Tilbaroo, Tyringham, Dundarrabin and Bostobrick told it is too late to leave.

The Peter Allen Festival, which is held every year in Tenterfield from September 5-8 is going ahead, despite some performers unable to access the area due to the fires.

An evacuation centre has been set up for residents at Tenterfield Showgrounds.

A grass fire raging in state's south is also at 'Emergency Warning' level in Cobargo.

Two fires remain at 'Watch and Act' level in the state's north.

The fires in northern NSW are producing large amounts of smoke which can be seen on satellite. Difficult conditions expected to continue this afternoon.

Sixty bush and grass fires continue to burn across NSW, 19 of which are uncontained. Strong winds across the state are also limiting access in and out of fire zones due to fallen trees on roads in the area, with gusts up to 100km/h causing "erratic fire behaviour".

Premier Gladys Berejiklian said the "severity" of the fires tell of the "horrific bushfire" season ahead.

"I'm certainly confident we have all the resources we need but nothing can match nature," she said. "The briefing that the minister and I recieved is very sobering because the wind conditions are such that you can't predict where the fire front is going."

"To know that there are still 19 uncontained fires in our state is still cause for concern. The commissioners believe that we are possible through the worst of it but that's not to say things can't change overnight."