Australian authorities have declared a state of emergency across a broad swathe of the country's east coast, urging residents in high risk areas to evacuate ahead of looming "catastrophic" fire conditions.
Bushfires burning across New South Wales (NSW) and Queensland states have already killed three people and destroyed more than 150 homes. Officials expect adverse heat and wind conditions to peak at unprecedented levels tomorrow.
Bushfires are a common and deadly threat in Australia's hot, dry summers but the current severe outbreak, well before the summer peak, has caught many by surprise.
"Everybody has to be on alert no matter where you are and everybody has to be assume the worst and we cannot allow complacency to creep in," NSW Premier Gladys Berejiklian told reporters in Sydney.
The country's most populous city has been designated at "catastrophic fire danger" for today, when temperatures as high as 37C are forecast to combine with powerful winds for potentially deadly conditions. It is the first time Sydney has been rated at that level since new fire danger ratings were introduced in 2009.
Home to more than five million people, Sydney is ringed by large areas of bush land, much of which remains tinder dry following little rain across the country's east coast in recent months.
"Tomorrow is about protecting life, protecting property and ensuring everybody is safe as possible," Ms Berejiklian said.
Lawmakers said the statewide state of emergency - giving firefighters broad powers to control government resources, force evacuations, close roads and shut down utilities - would remain in place for seven days.
This afternoon local time, the fire service authorised use of the Standard Emergency Warning Signal, an alarm and verbal warning that will be played on radio and television stations every hour.
NSW Rural Fire Service (RFS) Commissioner Shane Fitzsimmon surged people to evacuate before conditions worsened, warning that new fires can begin up to 20km ahead of established fires.
"Relocate while things are calm without the pressure or anxiety of fires bearing down the back door," he said.
Authorities stressed that even fireproofed homes will not be able to withstand catastrophic conditions, which Mr Fitzsimmons described as "when lives are lost, it's where people die".
More than 100 schools will be closed tomorrow.
Today rescue services are moving large animals from high risk areas, while health officials warned that air quality across NSW will worsen as winds blow smoke from the current mid-north coast bushfires south.
The fires have already had a devastating impact on Australia's wildlife, with about 350 koalas feared dead in a major habitat.
Australia's worst bushfires on record destroyed thousands of homes in Victoria in February 2009, killing 173 people and injuring 414 on a day the media dubbed "Black Saturday".
The current fires, however, come weeks ahead of the southern hemisphere summer, sharpening attention on the policies of Australia's conservative government to address climate change.
Environmental activists and opposition lawmakers have used the fires to call on Prime Minister Scott Morrison, a supporter of the coal industry, to strengthen the country's emissions targets.
Mr Morrison declined to answer questions about whether the fires were linked to climate change when he visited fire-hit areas in the north of NSW over the weekend.
Deputy Prime Minister Michael McCormack has accused climate activists of politicising a tragedy at the expense of people in the danger zones.
"What we are doing is taking real and meaningful action to reduce global emissions without shutting down all our industries," Mr McCormack told Australian Broadcasting Corp radio.
"They don't need the ravings of some pure, enlightened and woke capital city greenies at this time, when they're trying to save their homes."