SYDNEY - Australia's southeast sweated in a heat wave that intensified on Sunday, elevating bushfire risk and prompting authorities to issue fire bans for more parts of Victoria state.

Australia is in the grips of a high-risk bushfire season, with firefighters last week battling a large blaze that ripped through Victoria's Grampians National Park, razing homes and farmland.

The nation's weather forecaster warned that temperatures could reach 45 degrees Celsius (113 degrees Fahrenheit) in some parts of Australia's second most populous state of Victoria on Sunday. The mercury in state capital Melbourne was forecast to hit 38°C (100 F).

In the state's northwest, in the town of Mildura, where the temperature was predicted to reach 42°C (107 F), it was already 32.9°C (91 F) at 10:30 am, surpassing the January mean maximum temperature, according to forecaster data.

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The heat sparked total fire bans for three Victorian districts where authorities labelled the fire danger as "extreme", the second highest danger rating.

Bureau of Meteorology official Miriam Bradbury said temperatures would likely peak in Victoria on Sunday.

"What that means for the fire dangers is we are seeing a spike across more districts," Bradbury told Australian Broadcasting Corp television.

The states of Western Australia, New South Wales and Tasmania were also under heat wave warnings on Sunday, the forecaster said on its website.

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Bradbury on Saturday said a wind change bringing a cool change to the country's southeast was expected on Sunday night.

Australia's last few fire seasons have been quiet compared with the catastrophic 2019-2020 "Black Summer" of wildfires that destroyed an area the size of Türkiye, killing 33 people and billions of animals.