Most significant heatwave since black summer to blast Australia’s southern states as band of hot weather moves east

Parts of Victoria and SA could expect highs of 46 or 47C, with winds bringing bushfire danger later in week

Australia’s southern states are expected to bake this week as the most significant heatwave since the 2019-20 black summer pushes temperatures well into the 40s.

Heatwave warnings cover large parts of Western Australia, New South Wales, Victoria, Queensland, South Australia, Tasmania and the Australian Capital Territory as a band of severe to extreme heat makes its way slowly across the country, from west to east.

Wednesday would mark the start of a three-day period of extreme conditions for south-eastern Australia, said Dean Narramore, a senior meteorologist at the Bureau of Meteorology.

“We’re likely to see temperatures 8 to 16C above average through parts of South Australia, Victoria and New South Wales,” he said, which translated to temperatures in the mid-to-high 40s through inland areas and low 40s nearer the coast.

“It’s looking like the most significant heatwave for south-eastern Australia since the summer of 2019-20,” he said.

That would initially be “baking, searing heat” without much wind but, as the wind picks up from Thursday, high to extreme fire danger is expected for much of South Australia and Victoria.

By midweek, Adelaide and Melbourne could see temperatures peak in the 40s, with inland areas even hotter.

On Thursday parts of north-west Victoria and eastern SA could expect highs of 46 or 47C.

The heat is expected to linger across the south-east, with many places anticipating a run of days with temperatures in the mid-40s.

A cool change moving into SA on Friday would push the heat across into NSW, with Sydney temperatures peaking at 39C on Saturday.

With hot days and warm nights extending over multiple days, Narramore reminded people to take precautions: “Stay cool, stay hydrated, stay indoors, and also just be more aware of the elderly, the young, and also your pets as well. They’ll be feeling it if they’re outside.”

Narramore said the monsoon trough over northern Queensland and a high pressure system over the Tasman Sea had combined to create a “blocking pattern” that allowed the trough moving through from the west to funnel heat into the country.

Rain and storms were expected to continue in north Queensland, with multiple flood warnings remaining in place, including major flood warnings for the Flinders and Western rivers.

Australia’s national annual average temperature is about 1.5C higher than in 1910, according to the BoM, and the climate crisis has increased the frequency and severity of extreme weather events, including heatwaves and bushfires.

Cover photo:  Wednesday will mark the start of three days of extremely hot weather for south-eastern Australia, the BoM says. Photograph: Dave Hunt/AAP