Strong winds have brought a dusty haze to the east coast of NSW, reducing the air quality to hazardous in some areas.
It is the latest in a series of dust storms that have affected NSW after a prolonged run of drier than usual weather throughout most of last year.
Weatherzone warned the air quality may deteriorate in some areas before it improves when a change moves through later on Wednesday.
Weatherzone meteorologist Graeme Brittain said hot, dry, gusty north-westerly winds have brought the dust to the coast.
"It picked up the dust lying on the ground and then has vectored it - moved it - south-eastwards across NSW so it has arrived over Sydney over the last several hours," he said.
Mr Brittain said the dust, which moved across Canberra on Tuesday afternoon, was also affecting air quality across the state.
The air quality in the Albury and Wagga Wagga areas was twice the level considered to be hazardous on Wednesday morning, according to the Office of Environment and Heritage.
The Illawarra region recorded an air quality index value of 207, while Sydney's south-west recorded a very poor reading of 196 between 5 and 6am. A good value is considered between 34 and 66.
Sydney’s north-west, the lower Hunter and upper Hunter regions had poor air quality and Sydney’s east was fair, however Mr Brittain said conditions there could worsen before they improve.
"We could expect a deterioration in Sydney's east in the next few hours before it improves," he said.
The meteorologist said the dust is expected to hang over the city for most of the morning, but conditions are forecast to improve later in the day as the strong cold front moving across the south-east of Australia moves further north and east.
"We're seeing a ridge of high pressure build across the south-east of Australia in the system's wake, and that’s moving clearer, fresher air across NSW, across the Sydney area, so probably by this evening we'll see a marked increase in improving air quality," Mr Brittain said.
The hot, dry and gusty winds have also made conditions difficult for firefighters battling two large out-of-control bushfires in the state's north-east.
Rural Fire Service Deputy Commissioner Rob Rodgers confirmed a number of properties have been lost as crews continue to fight the fires at Tabulam and Tingha.
There were more than 43 fires burning across NSW on Wednesday morning, and nine of those remain uncontained.
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