Fire crews have the upper hand on flames burning north of Newcastle and in the Hunter Valley.

Several elderly people were evacuated from their homes in Rosemount Drive, Raymond Terrace, when a grass and bush fire jumped the nearby Pacific Highway on Tuesday afternoon.

By 8pm (AEDT) more than 50 hectares had been burnt as fire crews continued to work on containing the fire.

"It's not completely contained," Rural Fire Service spokeswoman Rebel Talbot told AAP.

"We've managed to get the upper hand on it.

"There's still a number of hours of work to be done and there is still a lot of smoke in the area.

"People need to be careful when they are driving on the road."

No properties were damaged or under threat on Tuesday evening and aircraft involved in fighting the fire were grounded at 7.30pm (AEDT).

Meanwhile a separate fire that threatened 10 homes on a road in the Hunter Valley has been contained.

Ten homes on Rosemount Road and Reg Thornton Memorial Drive, Denman, came under direct threat about 5.30pm (AEDT) on Tuesday.

"It was a really good effort from our ground crews and aircraft to contain that fire," Ms Talbot said.

"An emergency warning was issued for that fire, however (crews) were able to contain that fire about half an hour before it was going to impact."

No properties have been damaged by the fire.

A severe fire danger warning was issued for parts of the Greater Hunter, Greater Sydney, Illawarra/Shoalhaven, Central Ranges, Upper Central West Plains and Lower Central West Plains until midnight on Tuesday.

Some relief was expected on Wednesday, with cooler conditions forecast across the state.