A fire burning in Sydney's Hills district has been downgraded to advice level after earlier threatening homes.

An emergency warning was issued for residents in South Maroota, between Tuff Hill Lane and Gallaghers Road, north of Sackville Ferry Road, as the blaze was fanned by strong winds.

Firefighting aircraft were sent to help fire crews on the ground.

The blaze had been threatening properties but by 5.45pm, the NSW Rural Fire Service said it was "being controlled" and downgraded the threat level.

"Weather conditions continue to ease and rain has fallen across the fireground," the RFS said in the evening.

Firefighters said storm activity in the area previously created "erratic" winds.

RFS spokesman James Morris there were about 200 people believed to be in the area, which was mainly bushland and tourist drives.

An emergency text message was sent, Mr James added.

"There's very little housing in there, we do believe there is a nudist colony in through that location, which is the reason for sending that text message."

In the state's central west, more than 60 firefighters were working to slow the spread of a bushfire burning in the Goobang National Park, east of Parkes.

The fire had scorched more than 1,000 hectares, moving in an easterly direction towards the Bocobra area, the RFS said.

There were a number of isolated properties in the area, however there was no threat to homes.

The fire remained at watch and act level in the late afternoon.