A number of fires have merged into a mega blaze north of Sydney with 108 burning across NSW with 74 yet to be contained.
There are seven fires at emergency level, including the huge 250,000-hectare bushfire at Gospers Mountain – northwest of Sydney – which has joined up with the neighbouring Little L Complex and Paddock Run blazes.
Emergency warnings are also current for the Kerry Ridge fire in the Wollemi National Park, the Carrai East blaze northwest of Kempsey, the Green Wattle Creek fire southwest of Sydney, the Meads Creek West blaze in the Upper Hunter Region, Wrights Creek on the Central Coast, and the Bangala Creek bushfire near Tenterfield.
There are additionally seven major blazes at "watch and act".
More than 2800 firefighters are currently fighting blazes.
Properties may have been lost and damaged on Thursday – particularly at Bawley Point north of Batemans Bay – but exact figures won't be known until assessment teams can safely enter the burned-out areas.
NSW Premier Gladys Berejiklian told reporters resources were being “stretched across the entire coastline”.
"We've also seen the fire come into very close proximity to major population centres,” she said.
Six people have died so far this fire season while more than 680 homes have been lost.
Ms Berejiklian said many families had been forced to leave their homes as some 2000 firefighters continued battling blazes on Friday supported by 100 aircraft.
"Our thoughts are with the people who have been displaced and people who are living in fear ... and we have to acknowledge many people throughout the state are," the Liberal leader said.
Crews have come from interstate as well as New Zealand and Canada to help fight the fires. A team from the United States will arrive on Saturday.
NSW Rural Fire Service commissioner Shane Fitzsimmons said Friday would be "another extremely busy day" with temperatures reaching into the high 30s in some places coupled with very low humidity.
"We can't overstate the effect that this profound drought is having... on the flammability of the fuel," he said.
"You are seeing fires start very easily and they are spreading extremely quickly and they are burning ridiculously intensely."
The commissioner said Sydney could remain blanketed in smoke for weeks if not months given it's now ringed by fires.
"Unless we are blessed with good, strong, easterly winds – which would push any smoke burning from fires into the west of NSW – we are going to continue experiencing smoke inundation along the coastal strip of this state for some time yet," Mr Fitzsimmons said.
He added smoke from the fires was drifting "all the way across to New Zealand and being captured and reported on satellites as impacting communities that far away”.
Differing opinions on climate change
Ms Berejiklian has repeatedly said now is not the time to talk about the impact of climate change on bushfires.
But according to a UNSW community survey released on Friday, some 53 per cent of respondents say it is right to talk about global warming during extreme events.
Just 35 per cent of Australians surveyed said it was not okay.
Thousands of calls for breathing difficulties, asthma
Ambulance call-outs and trips to emergency departments for people struggling to breathe amid the smoke haze smothering NSW are higher than usual for the third consecutive week.
NSW Ambulance fielded some 2330 calls for help with asthma or breathing difficulties over the past week - 30 per cent more than an average week.
Over the same period, hospitals across the state saw a 25 per cent increase in emergency department presentations for respiratory issues.
There were 1140 presentations, with the biggest spike occurring in the hardest-hit southwestern Sydney area.
Student Sophie Gibbons, who lives in Sydney's north, says the lingering smoke over the past few weeks has made it nearly impossible for asthmatics to go about their daily lives.
"It's like I'm breathing in soup, or breathing through a straw," the 20-year-old told AAP on Friday.
"Walking anywhere outside makes me feel breathless, even if it's just a few metres to the letterbox."
Ms Gibbons can't remember a time she's had to use her ventilator so often.
“My nan is very worried about me. She keeps sending me messages, saying: ‘Stay indoors today.’ But the smoke is just everywhere. It's even getting inside our house,” she said.
NSW Health environmental health director Dr Richard Broome says people with asthma, emphysema and angina should avoid outside activity. Face masks provide little protection.
"NSW Health continues to recommend that people with these conditions should avoid outdoor physical activity when there's smoke around," Dr Broome said in a statement on Friday.
The main concern with the smoke is minuscule PM2.5 particles which are so tiny they pass through most masks.
"A P2 mask does filter out these particles but is only effective if there is a good fit and an air-tight seal around the mouth and nose," Dr Broom said.
"Evidence shows that this is difficult to achieve in practice so they may not provide the benefits people are hoping for."
Vets have also urged owners' to keep their pets inside to avoid the smoke.
"If it is uncomfortable for a human to breathe, then it is uncomfortable for pets too," RSPCA NSW spokeswoman Sharon Andronicos said in a statement.
Sydney's east and southwest were rated "very poor" and "hazardous" for air pollution on Friday while the northwest was "fair".
The NSW environment department said this season's bushfire emergency has caused "some of the highest air pollution ever seen in NSW".
Fires rage across Queensland
Two homes have been gutted as bushfires rage across Queensland, with heatwave-conditions gripping the state.
Much of the state is sweltering, with temperatures expected to reach about 12C above the December average in coming days, the Bureau of Meteorology says.
On Friday afternoon, people living around Mount Stanley, east of Kingaroy, were told to leave their homes.
The fast-moving fire is burning in the vicinity of Landcruiser Mountain Park, and is expected to impact campers in Landcruiser Mountain Park.
They are being told to leave via Diaper Road.
The severe fire conditions have emergency crews on alert as more than forty fires raged on Friday.
"Our people are tired, and our people have been working at this a long time now, but the spirit and the moral is still there," QFES acting assistant commissioner Darryl King said.
He says the conditions have been unrelenting for crews and officials.
"We're getting pockets of extreme weather ... days following after days, week after week," Mr King said.
"I ask everybody to be very careful, very vigilant on the situation around them, call any fires they see, at the earliest moment, so that we can put the weight of attack on and extinguish them."
Fifteen crews were fighting a massive blaze in the Queensland Darling Downs on Friday morning.
Authorities say the fire has destroyed 10 buildings, including two houses that were gutted by the inferno.
The fire which forced residents at Forest Ridge and Cypress Gardens, near Millmerran, to flee their homes had blackened almost 1200 hectares as of Friday afternoon.
Up to fifty homes and more than 200,000 hectares have been burnt across the state since the beginning of the unprecedented bushfire season in September.
"What we don't count is the number of houses our crews save," Fire and Emergency Services Minister Craig Crawford said.
"I think if you were to go out there in the last three months and count that it would be many, many hundreds, if not into the thousands."
Mr Crawford said a fleet of aircraft helping fire crews on the ground would in previous seasons have left Queensland for the southern states by now.
"We've kept most of those through until the end of January at least, at very large expense obviously to the state, as well as the ongoing bill that we're carrying with wages and operations," he said.
"But it's worth it, we've got to do it, we'll deal with the dollar figure at the end of it."
Queensland is set for a scorcher on Saturday as the heatwave gripping the state reaches its peak.
Brisbane is forecast to hit 39C, while inland areas of the south east including Gatton and Ipswich are expected to hit well over 40C.
The Darling Downs, Maranoa and Warrego regions are forecast to be the hottest areas in the state, with towns reaching temperatures eight to 12 degrees above the December average.
- with AAP
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