A total fire ban has been declared for Australia’s most populated city, where preparations for what is expected to be a challenging summer bushfire season are well underway.

Flames drove thick smoke from hazard reduction burns in Sydney’s north on Friday, pictures from the 7NEWS chopper showed.

Crews had planned burns at the Sphinx Trail in North Turramurra, McCrae Pl in the same suburb and Quarry Rd in Hornsby.

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All fires are under control on a spring day the weather bureau said had been sunny with a top of 24.1C.

There will be an elevated fire danger on Saturday due to unseasonably warm (31C) and windy conditions, and a total fire ban has been declared for Greater Sydney.

“No fires may be lit in the open and all fire permits are suspended during a total fire ban,” NSW Rural Fire Service said.

The ban commences at midnight.

Fire crews have carried out hazard reduction burns in the city's north on Friday. Credit: 7NEWS

Fire crews have carried out hazard reduction burns in the city's north on Friday. Credit: 7NEWS

Authorities say hazard reduction burns like those on Friday are “an important part of preparing for bushfires” and help “protect people, property and the environment”.

“With El Nino conditions established, there is a high potential for a challenging summer with forecasts indicating an increased likelihood of above-average temperatures and below-average rainfall,” the NSW government said in August.

“Warmer and drier-than-average conditions during autumn have left many parts of NSW unusually dry, with some regions already experiencing drought.

“If these conditions persist, fire activity could increase through spring and into the 2026–27 bushfire season. 

“Inclement weather and increasingly unpredictable bushfire seasons are reducing the windows available to undertake hazard reduction, highlighting the need to look at new ways to prepare for the start of the bushfire season.”

Fire crews have carried out hazard reduction burns in the city's north on Friday. Credit: 7NEWS

Sydney has reached a top of 24.1C on Friday. Credit: 7NEWS

Emergency service agencies say they have carried out hazard reduction on more than 124,000 hectares of public and private land since July, 2025, helping to shield more than 174,000 properties from danger down the track.

The state’s rural fire service says the “best information and forecasts” are used to minimise impact on nearby residents, but it can be “difficult to predict where smoke will spread”.

“Smoke from bushfires and hazard reduction burning can affect some people more than others,” the service said.

“Children, older adults and people with heart and lung conditions are most susceptible to the effects of air pollution and excessive smoke.

“If you have asthma or a lung condition, reduce outdoor activities if smoke levels are high and if shortness of breath or coughing develops, take your reliever medicine or seek medical advice.”