Soaring temperatures are set to lead to record power demand in Queensland.
But the state government insists the energy grid will hold up as Queenslanders try to beat the heat indoors.
Parts of the sunshine state are sweltering on Monday as inland areas reach more than 40C, with numerous coastal and southeast centres recording mid-to-high 30C temperatures.
Birdsville hit 40C by mid-morning, with a high of 44C expected.
The mercury also rose at Bowen, Birdsville, Bundaberg, Brisbane, Gladstone, Ipswich and Longreach.
"Birdsville didn't get very cool overnight either, it didn't really get below 30C," the Bureau of Meteorology's Daniel Hayes told AAP on Monday.
"There was not really any relief overnight out that way."
Brisbane is expected to swelter through temperatures 8C above average with the state capital set to peak at 37C.
Energy Minister Mick De Brenni said Queensland's previous record for peak power demand was 10,070 megawatts set in March 2023.
He expected that to be "surpassed significantly" between 5.30pm to 7.30pm on Monday when Queenslanders seek heat relief when they return home from work.
"We can assure Queenslanders that there remains adequate supply of power," Mr De Brenni said.
"Of course it will be very, very tight.
"For the time being Queenslanders can rest assured that the lights will stay on and we will have adequate supply to meet that demand."
The Queensland Ambulance Service said their workload had already increased with the onset of the heat.
"We've mobilised every resource possible," medical director Stephen Rashford said.
"We'll see more cardiac arrests today than we will see on other days.
"It's going to be one of our busiest days ... we all felt the heat over the weekend, it was unbearable."
For parents of returning school students, ensuring access to water and sun safety is paramount.
"Have a general chat with them, let them know to keep up their water ... and if they do start feeling headaches or tummy upsets, just to let someone at school know," the ambulance service's senior operations supervisor Matthew Hannabery said.
Education Minister Di Farmer described air conditioning in schools as 'absolutely critical' and said the state's teachers are very conscious of the impact of heat on children.
"Teachers will be doing really practical things like making sure students aren't spending too much time in the sun, to make sure they're drinking water, and we just encourage parents to really talk through those things with their children as well."
A cool change will bring relief for Queensland's southeast on Tuesday, with Brisbane expecting 29C.
Further inland, the bureau said conditions will still be sweltering until the weekend, with Birdsville expecting 46C on Tuesday and 47C on Wednesday.
The bureau has issued an extreme heatwave warning for the northwestern pastoral district of South Australia, with temperatures expected in the low to mid-40C.
Severe to low-intensity heatwave conditions are expected across much of the rest of SA and into southern parts of the Northern Territory.
Parts of NSW are also expected to swelter in the coming days. Areas in the north of the state, including Moree, could reach temperatures above 40C.
WA has already been sizzling, with temperatures stretching through to 50C in some areas of the Pilbara at the weekend.
A few more days of high temperatures are forecast for the Pilbara and northern Gascoyne regions, but the heatwave is expected to ease from Wednesday.
