NSW air quality to get worse as windy, dry conditions fan bushfire threat

Firefighters are facing tough conditions and the Sydney basin is again forecast to be smothered in smoke from surrounding bushfires.

A Skycrane over an out of control fire at Avery's lane, near Stanford Merthyr, west of Newcastle. Source: AAP

Firefighters are facing tough conditions while bushfires surrounding Sydney will again pollute air quality in parts of the city.

Warm, dry and windy weather is forecast for the state on Wednesday, with total fire bans in place for the greater Hunter region, the northern slopes region and northwestern NSW.

Fire danger ratings are very high along the NSW coast as well as in the southern and central ranges.

"Windy and generally dry conditions will result in elevated fire dangers across parts of NSW (on Wednesday)," the Bureau of Meteorology said.

Firefighters battle to contain a fire at Currowan. Source: NSW RFS

The state government has again forecast "poor" air quality for parts of Sydney, with thick smoke settling in the city basin.

Lingering smoke could be "unhealthy for sensitive people, and could cause symptoms, especially in people with heart or lung disease", the state's environment department said.

Air quality was "hazardous" in Sydney's east and southwest on Tuesday but "good" in the northwest.

The smoke is coming from large bushfires in the Blue Mountains and others near Warragamba Dam, and in the Hawkesbury area.

There were some 111 fires burning across NSW on Tuesday evening, with 54 of these uncontained.

The Currowan blaze near Batemans Bay has so far destroyed at least one home near Kioloa.

A haze hangs over Sydney due to out-of-control bushfires. Source: AAP

The fire reached coastal areas on Tuesday evening.

Damage assessment teams investigating the impact of the Currowan fire have so far been hampered by ongoing dangerous conditions.

"The fire has reached the coast in some areas," The NSW Rural Fire Service said on Tuesday evening.

"Firefighters and aircraft are working to protect homes where possible."

The Currowan fire has burnt through more than 30,000 hectares.

A second emergency alert was issued on Tuesday night for a bushfire burning near the northwestern outskirts of Sydney.

The 1800-hectare Three Mile fire is near the town of Wisemans Ferry and is close to the eastern boundary of the 220,000-hectare Gospers Mountain blaze.

The emergency warning was downgraded to a watch and act alert later on Tuesday night.