Brace yourself, Australia: it’s going to be like an oven out there for large swathes of the country.

Parts of Australia’s south and east will swelter through 40-plus temperatures today as severe heatwave conditions continue to develop.

The Bureau of Meteorology says a severe heatwave is moving through the southern parts of South Australia and much of Victoria, while spreading further east into New South Wales’ coastal regions and south-west Queensland, which is anticipating several days of extreme heat.

Mildura and Swan Hill are expected to reach 44C today, prompting fire bans and heat health warnings for the Mallee and Wimmera regions.

There is also a total fire ban in the Central region and heat warnings for East Gippsland.

It will only be slightly cooler in Melbourne with a forecast maximum of 37C the Victorian capital’s hottest day of the season so far.

A cool change for Melbourne will arrive in the afternoon, but the weather bureau’s Dr Chris Godfred says the hot air is expected to hang around the north of the state well into the weekend.

“Albury’s expecting a top of 43C Friday and then 40C, 41C along the Murray River during Saturday,” he said.

“The air mass is quite humid. It’s going to limit the degree of cooling. Conditions as we try to sleep, especially Thursday night, [are] going to be quite stifling.”

Firefighters have spent the night monitoring hot spots after a grassfire at Diggers Rest, in Melbourne’s north west.

While the fire is under control, authorities have issued an advice message for residents in Diggers Rest and Calder Park to monitor conditions.

Firefighters have also brought a bushfire under control overnight at Amphitheatre, near Lexton, in the state’s west.

The heatwave in New South Wales is expected to reach severe and extreme levels towards the weekend.

South Australia is in for a second hot and muggy day with the temperature in Adelaide expected to hit 42C again today, and Tarcoola in the state’s north tipped to reach 47C.

The mercury in Adelaide hit 42.4C yesterday and senior forecaster Tom Boeck says inland areas will remain hot and sticky today.

He says the state will not see much relief from the heat until late on Saturday or early on Sunday.

“Certainly it will be feeling quite humid today with moisture still pushing down from the north,” he said.

“Unfortunately the evap aircon like I have won’t be working too well today, but hopefully in the overnight period they’ll be functioning a bit better with the temperatures coming down a touch.”

South Australia’s Energy Minister Tom Koutsantonis wants answers from the Australian Energy Market Operator .

More than 40,000 homes were without power for more than half an hour after SA Power Networks was instructed to begin load shedding because of a lack of available generation.

Mr Koutsantonis says despite the extreme heat that had been forecast days ago, the national operator failed to turn on extra generation at Pelican Point.

“We knew that we were heading into a very, very high-demand evening [with] very, very hot winds and very, very hot conditions,” he said.

“We should’ve had all of our available generation on and operating, and for whatever reason the market operator didn’t turn on all that generation and we were left short for 27 minutes, and that’s unacceptable.”

The Australian Energy Market Operator has been contacted for comment.

Queensland students kept indoors

Students at a school in south-west Queensland are having to spend lunchtime indoors as temperatures soar above 40C. 

St Patrick’s primary school in St George has implemented a “hot weather policy” where students stay in their air conditioned classrooms once the temperature hits 42C. 

Principal Brendan Redinger says keeping the students cool is crucial to their learning.

“If they’re running around, you know, even in the shade, it’s hot. So we have to be mindful of these students and help them out with their regulation of temperature,” he said.

“So by looking after them and keeping them cool and calm in this situation we’re getting the best out of them.”

Temperatures in St George are expected to reach 45C.

In contrast to the heat, the West Australian town of Karratha has recorded its wettest February day on record.

A tropical low which crossed the Pilbara coast at midday on Wednesday dumped more than 208 millimetres of rain on the town.

The low is currently south-west of Karratha and moving parallel to the coast.

– ABC/Weatherzone