An out-of-control fire sparked by embers from a blaze in the ACT is testing NSW firefighters as health experts warn poor air quality will affect parts of the state, including Sydney.
NSW Health is warning of the impact of smoke haze and dust on Sunday, with Sydney's air quality forecast to be poor due to particles.
"A change in wind direction is likely to bring smoke from the southern NSW and ACT bushfires into eastern parts of Sydney, the Illawarra, and possibly the Central Coast and Newcastle this morning," NSW Health said in a statement on Sunday.
The department's medical advisor Dr Adi Vyas said dust from dust storms in western NSW may affect western Sydney.
"People with chronic respiratory and cardiovascular conditions should avoid outdoor physical activity and those with asthma should also follow their Asthma Action Plan and carry their reliever medication with them," Dr Vyas said in a statement.
"Minimising physical activity, staying indoors and knowing your treatment plan are important ways to reduce the risk of dust and smoke-related illness.
"Ongoing heatwave conditions means that we all need to take extra care over the coming days."
On Sunday morning four fires were at "watch and act" level.
The out-of-control Clear Range blaze, created from embers that spread from the ACT's large Orroral Valley blaze, had been downgraded to "advice" level.
An RFS spokeswoman on Saturday night said there had been unconfirmed reports of possibly five structures lost.
Very high fire danger is forecast for Sunday for the north coast, greater Hunter, greater Sydney, Illawarra/Shoalhaven, central ranges, northern slopes and north western fire regions.
"Storms, possibly severe, are forecast for many parts of NSW on Sunday including Sydney. Storms inland may raise dust," the NSW Bureau of Meteorology posted on Twitter on Saturday night.