Extreme fire danger warnings are in place for parts of New South Wales (NSW) and nine total fire bans are in place, with strong winds and soaring temperatures expected to worsen conditions.
More unseasonable spring heat is building up across Australia's eastern seaboard, with a hot weekend across much of the country ahead of an expected cool change later this week.
Adelaide reached 32C on Saturday, and extreme fire conditions were in place for the West Coast district with hot, dry and gusty northerly winds.
The AFL grand final was played in 29C in Melbourne on Saturday afternoon, one of the hottest grand finals ever.
The Bureau of Meteorology said severe winds began impacting southeastern parts of Victoria on Saturday and were expected to push up the coast overnight into Sunday.
Damaging winds are then expected in the Snowy Mountains and parts of the NSW south coast, the southern tablelands, southwest slopes, and the Australian Capital Territory (ACT).
The northwestern and upper central west plains of NSW, the Greater Hunter, Greater Sydney, and far south coast regions are facing extreme fire danger conditions.
The NSW Rural Fire Service has declared nine total fire bans for the state on Sunday from the northern slopes down to the border with the ACT and Victoria.
Five separate regions are declared at extreme risk of fire, with high temperatures, strong winds and low humidity combining to raise the risk.
Temperatures are forecast to reach up to 36C in Sydney's west, where the NRL grand final is due to get under way in the evening.
Hot weather provisions such as extended breaks and cold towels and fans for the players will be in place for the match, with tens of thousands of people expected to attend.
Queensland Fire and Emergency services are battling blazes from Townsville down to the Gold Coast, with another fire burning at Camooweal near the Northern Territory (NT) border.
A fire weather warning is also in place for the NT's Simpson East region for Sunday.