Firefighters are said to be facing a long battle after the Rural Fire Service on Friday night issued emergency warnings for fires at Tenterfield, Drake and Legume in northern NSW and Bees Nest near Armidale.

RFS spokesman Anthony Bradstreet said they had received reports of property losses in Tenterfield, and a volunteer firefighter had been airlifted to hospital with burns to his hands and throat.

There have been no other reports of death or injury.

He said 760 firefighters had been deployed as of Friday night in response to blazes across the state - and their battle could continue for weeks.

Conditions were very challenging, with firefighters contending with dry conditions from prolonged drought and strong winds through the fire grounds.

"What we're worried about, moving into the evening, is a strong south-westerly change which is going to be moving through the Tenterfield-Armidale areas over the next few hours," Mr Bradstreet told AAP on Friday night.

That strong southerly change has the potential to push fires more towards the north-east which we're watching very closely."

For residents near the Tenterfield and Drake bushfires, it was too late to leave on Friday night.

The bushfire at Bees Nest, meanwhile, had burned through more than 16,000 hectares.

It came as a total fire ban was declared across Sydney and much of NSW's north due to warm, dry and windy conditions.

RFS commissioner Shane Fitzsimmons told reporters: "Records will indicate we have never seen in NSW, fire danger ratings in this part of the state to the level we're experiencing here today".

Mr Bradstreet said that while conditions may ease somewhat going into the weekend, most of north-east NSW would still sit in the very high fire danger range on Saturday.

"In terms of the impact on these fire grounds, they're going to be fighting these fires for, I'd be suggesting weeks," he said.

"Some of these fires are very large and with no rain on the horizon at the moment, this is going to be a very long battle for firefighters in the field."

Australian Associated Press