The number of NSW homes lost to bushfires this season has passed 600 as crews continue to battle 50 blazes across the state which have again blanketed Sydney in smoke.
An emergency warning for an out-of-control bushfire was issued on Thursday afternoon for a blaze burning between Bora Ridge and Whiporie on the state's north coast.
It has so far burned 34,000 hectares and is spreading towards Whiporie, Camira, Tullymorgan and Jacky Bulbin Flat, the NSW Rural Fire Service says.
The service on Thursday revealed 612 homes have been destroyed to date. The fires have also claimed six lives this bushfire season.
Some 503 homes have been destroyed in the past fortnight while 178 have been damaged.
In the same time period, 1300 outbuildings have been damaged or destroyed.
Thick smoke enveloped Sydney and much of the NSW coast on Thursday morning pushed by northeasterly breezes. People with chronic respiratory or heart conditions were warned to stay indoors.
"If you do develop symptoms and they don't get better with your normal reliever medication you should seek medical advice and in an emergency you should call triple zero," NSW Health environmental health director Dr Richard Broome said.
Air quality for parts of Sydney remained hazardous on Thursday afternoon. It was also hazardous in the northern tablelands and the northwest and southwest slopes.
The RFS said smoke was being mixed with dust from the state's west.
A southerly change is forecast to hit Sydney on Friday morning which will clear away the smoke, a Bureau of Meteorology spokesman said in a statement on Thursday.
"That means as we move into the weekend the chance of smoke is quite is low," he said.
There is, however, the chance of smoke haze developing on Saturday morning particularly in Sydney's western suburbs but it should clear throughout the day.
Some 50 bushfires are still burning in NSW - 20 of which are uncontained. More than 1000 firefighters remain in the field.
There are 12 total fire bans in place across the state.
Several fires were upgraded to "watch and act" level on Thursday afternoon including the 170,000-hectare blaze at Gospers Mountain northwest of Sydney.
"Watch and act" alerts ae also in place for small fires west of Armidale in the Northern Tablelands and west of Albury on the Victorian border.
A severe fire danger rating is in place for 10 areas including Illawarra-Shoalhaven. The entirety of the state's south is under "very high" or "severe" fire danger as hot winds blow in from South Australia.
Winds of up to 60km/h are forecast across the southern border region which could present challenges if there are new fires, RFS commissioner Shane Fitzsimmons said.
"It's another difficult day for firefighters, for people in these at-risk areas," he told the Seven Network.
But, after a fortnight of deadly fires, he's hopeful conditions will improve.
"Once we turn the corner on today there'll be an easing of conditions more broadly across the state," Mr Fitzsimmons said.
© AAP 2019