Several out-of-control fires are raging north, south and west of Newcastle, forcing the closure and evacuation of the airport with authorities advising people in some threatened areas to leave.
There are also reports a fast-moving intense fire near Ruttleys Road at Doyalson, near Wyong, has ignited a fuel store and caused an explosion.
A 2000-hectare bushfire at Muswellbrook that's out of control was at 8.50pm (AEDT) threatening properties.
Residents have been advised to leave the area.
"Firefighters are undertaking property protection under difficult, dangerous and erratic weather conditions," the RFS says on its website.
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"Residents are advised to leave now unless your property is properly prepared."
Publican Brett Jaeger said there was a "pensive" mood among the 60 people sheltering at the Caves Beach Hotel, south of Newcastle.
Several people there aren't sure whether their homes have been destroyed by fire and they can't leave to check as local roads are closed, he said.
"They're very concerned at this stage because it's a big area here with a big bushland area," he told the ABC.
"Everybody's just waiting and watching at this stage."
Emergency warnings are in place for an out-of-control 2819-hectare scrub fire at Heatherbrae and a 945-hectare scrub fire at Doyalson.
A "watch and act" alert, one level short of an emergency warning, is also in place for a one-hectare scrub fire at Glendale that is burning out of control.
A five-hectare bushfire on the Pacific Highway at Heatherbrae is being brought under control, but a "watch and act" alert has been issued by the RFS.
There has been unconfirmed property losses in the area and Rural Fire Service Commissioner Shane Fitzsimmons has warned the public the damage would be significant.
The Transport Management Centre has advised people to delay all non-essential travel through the Hunter and Lake Macquarie region with several main roads closed.
The Pacific Highway has been closed between Swansea and Wyee Road, Doyalson and the Newcastle Link Road has been closed between Lake Road and Minmi Road in Cameron Park and Wallsend.
