Firefighters are battling two emergency level bushfires in northern NSW, one of which has destroyed at least two properties and damaged a world-leading observatory, as 30 uncontrolled blazes burn across the state.
The emergency at Wambelong Camping Area has seen Mt Woorut residents and staff from the Siding Spring Observatory in Warrumbungle National Park evacuated to nearby Coonabarabran.
Firefighters' efforts to contain the blaze were being hampered by strong south-westerly winds in the area, an RFS spokesman told AAP on Sunday night.
"The wind conditions that are being experienced there are creating erratic fire behaviour for crews on the ground," the spokesman said.
Fire crews will assess the two properties destroyed on Timor Rd and the observatory damage on Monday morning, he said.
There are hopes that telescopes in the Siding Spring Observatory - the nation's top optical and infrared observatory - will survive the inferno thanks to a range of precautions including the use of special paint.
Dr Amanda Bauer, who works at the observatory, said she was "hopeful" the telescopes would survive the bushfire.
"Tomorrow we will see how well those protections held," she wrote on her blog on Sunday evening.
However, Nobel Prize-winning Professor Brian Schmidt, who also works at the observatory, said initial reports indicated the fire had caused a lot of damage.
"Fires are worse than I had feared ... bad day tomorrow," he wrote on Twitter.
The other emergency fire burning out of control on Sunday evening was centred on Bundabarina, about 10 kilometres west of Collarenabri on the Walgett Road.
Collarenabri residents have been advised to seek shelter and follow their bushfire survival plans, the RFS said.
Firefighters have issued watch and act warnings for two other fires. These are at Nangar Road in Eugowra, in the state's central west, and Rocky Glen Road in Bendemeer, in the New England area.
Meanwhile, a cool change has brought relief to RFS officers fighting fires in other areas.
More than 190 firefighters were working to contain a blaze 12km west of Sussex Inlet, near Shoalhaven on the south coast.
The fire has burnt more than 8400 hectares but there is no immediate threat to properties.
At Yarrabin, near Cooma, in the Snowy Mountains, more than 100 firefighters continue to establish containment lines and extinguish spot fires, with no threat to properties.
The fire has burnt through more than 12,000 hectares of bushland and is moving away from Cooma to the east.
Residents returning to properties have been warned to be aware of falling trees and branches, particularly in the Mt Forest Road area.
In the southern tablelands, more than 70 firefighters are working on containment lines around a fire near Yass. The blaze has been contained.
In the state's north about 20 fires are burning uncontained after lightning storms on Saturday night ignited 45 new fires.
