NSW fires LIVE updates: RFS battles blaze bigger than Sydney, hospitals see spike in smoke-related issues

Firefighters are battling more than 100 blazes across the state but the number of fires at emergency warning level dropped again late on Friday, from six to three.

• The bushfires that remain at emergency level are: Gospers Mountain, which joined with two neighbouring fires to create a "megablaze" covering an area greater than Sydney; Green Wattle Creek; and Wrights Creek.
• Seven areas of NSW have total fire bans in place from midnight tonight, including Greater Sydney, the Greater Hunter, the Central Ranges and the Far North Coast.
• Premier Gladys Berejiklian has warned conditions are expected to worsen around Tuesday, as she urged the community to "remain vigilant".

Sydney and the Greater Hunter are among five districts forecast to have very high fire danger on Saturday, while New England and the Northern Slopes were likely to have severe fire risks.

We'll resume our live coverage tomorrow.

Former Rural Fire Service Commissioner Phil Koperberg has warned NSW faces "a very dire situation" and the worst is to come as authorities are stretched to the limit battling raging bushfires including a megablaze covering an area larger than Sydney.

NSW Labor Opposition Leader Jodi McKay accused the government of being caught "absolutely flatfooted" and said "massive firefighting reinforcements are required".

"We are relying on weary volunteers working night after night. They are exhausted and they cannot be expected to sustain this effort indefinitely," she said.

Read more here.

Rural Fire Service Commissioner Shane Fitzsimmons said Sydney could remain blanketed in smoke for weeks, if not months, unless there was a significant change in wind.

The Bureau of Meteorology is providing air quality updates on its website.

While NSW Premier Gladys Berejiklian and her deputy John Barilaro have been tight-lipped about climate change while bushfires rage across the state, Malcolm Turnbull has been less circumspect.

On Friday the former Liberal prime minister posted an aerial photo of Sydney on Instagram and said: "The reality of climate change - hotter and drier means more fires.

"We have to accelerate the move to zero emission energy. It will mean a safer planet for our children and more affordable energy."

Former NSW Labor MP Emma Husar replied: "But if only you would have used your position, when you had it, to do those things."

Rural Fire Service Commissioner Shane Fitzsimmons has warned the drought and weather conditions mean difficult conditions for firefighting for "a long time ahead".

"Between now and February we can expect below average rainfall and above-average temperatures for this time of year, which, unfortunately, just signals increased fire danger, increased fire activity, particularly across a terribly drought stricken landscape," he said on Friday.

Sydney and the Greater Hunter are among five districts forecast to have very high fire danger on Saturday, while New England and the Northern Slopes are likely to have severe fire risks.

Tuesday's forecast is likely to be the next big test for fire crews with temperatures for much of inland coastal NSW likely to climb into the 40s. Sydney is expecting a maximum of 32 degrees on Tuesday and Penrith 43 degrees.

Residents are resorting to buckets of water to defend their properties southwest of Sydney.

Herald photographer Alex Ellinghausen is near Oakdale where he has captured these stunning images.

The NSW Department of Education has sent a fact sheet to principals about how to react to smoke, suggesting they consider alternative arrangements for staff and students "in the rare situations where there is a significant amount of bushfire smoke".

When there is poor air quality, schools should look for ways to minimise exposure, such as keeping staff and students inside for recess and lunch breaks, with windows and door closed.

Staff should consider cancelling sporting events and unnecessary outdoor activities, and keep students calm and avoid vigorous exercise, said the fact sheet, which was sent out on Wednesday.

Staff should also watch for symptoms such as itchy or burning eyes, throat irritation and shortness of breath. "It is important to identify students who have a diagnosed breathing condition," the guidelines said.