Firefighters and residents are on high alert near a northern NSW town surrounded by fast-moving bush and grass fires.
Four emergency warnings were issued for blazes around Tenterfield early on Tuesday afternoon as the fire front quickly shifted under strong, gusty westerly winds.
While the fires were still some way from the township, multiple rural properties were under threat, Rural Fire Service Commissioner Rob Rogers said.
"There are a number of properties that are going to be threatened this afternoon from all those fires," he told ABC News.
"They're very, very active. We've seen strong, gusty winds of 40, 50km/h."
The deteriorating conditions also threatened to help a dangerous Queensland blaze jump the state border 15km north of Tenterfield.
The Glen Innes RSL and Tenterfield Showground were opened to accommodate locals leaving before the forecast of extreme fire danger.
NSW fire crews were also concerned about the reactivation of the large Glens Creek Road fire southwest of Grafton, which was elevated to emergency warning level after jumping containment lines.
Firefighters and aircraft continue to protect properties in the area.
"It's going to be a really tense afternoon for both firefighters and residents," Mr Rogers said.
"We've got hours still to go of these conditions of hot winds, warm temperature, low humidity - all that is making firefighting both dangerous for firefighters and residents."
A cool change is expected to cross the fire ground at 6pm local time.
But it could take several more hours for the fuels to absorb the moisture and calm fire behaviour, Mr Rogers said.
More than 500 firefighters are working across the state.
Seven areas have total fire bans in place on Tuesday, including greater Sydney and the Hunter and Illawarra/Shoalhaven regions.
Extreme fire danger ratings are also in place in three districts along the Queensland border from New England to the west.
At midday on Tuesday, there were 77 fires burning across the state, 24 of which were yet to be contained.
Firefighters earlier battled a number of small grass and bushfires that broke out on Sydney's outskirts in the morning as powerful winds whipped through the city's west and south.
Fire and Rescue NSW Superintendent Adam Dewberry said the wind brought down a number of power lines, which could cause sparks and lead to bushfires.
He said fire trucks were moved to the city fringes in preparation for the high-risk conditions to provide a quick response to any initial flare-ups.
Australian Associated Press
Sign up for our newsletter to stay up to date.