Parts of Australia sweltered through temperatures peaking in their mid 40s as the weather bureau issued heatwave warnings for much of the country.
Severe heatwave conditions blanketed northern and central parts of South Australia, with the state's capital nudging just past 41C on Tuesday afternoon, the first day over 40C this year.
SA Premier Peter Malinauskas urged people to check in on their neighbours and particularly the elderly who can be more at risk in extreme heat.
"It's probably a good time for people to remember to look after themselves, look out for their neighbours, but look out for the elderly in particular, it has been a while since we've gone over that 40-degree threshold," he told reporters.
Temperatures in multiple towns in the mid-north, Flinders and Riverland regions climbed to the mid 40s with Port Augusta hitting 44.7C just after 3pm.
The coastal town of Ceduna west of the Eyre Peninsula reached a scorching 46.6C while nearby Wudinna hit 46.8C
Low to severe intensity heatwaves continued across much of the country.
Parts of upper western NSW nudged 40C, the highest recording of 41.7C at Smithville on the SA border.
Regions in the northwest slopes and plains including Walgett and Moree didn't fare much better, registering only 1C cooler about 3pm.
The Bureau of Meteorology said both maximum and minimum temperatures are forecast to be 5-12C above average throughout the rest of the week.
The severe heatwave conditions are set to spread east towards Sydney, the Hunter and Mid North Coast on Wednesday and Thursday.
The state capital is expected to reach the mid-30s on Thursday and Friday, while Penrith in the city's west will be closer to 40C.
NSW State Emergency Operations Controller, Deputy Commissioner for Emergency Management Peter Thurtell urged people to look after their health and to watch out for heatstroke or heat exhaustion.
But Bureau spokeswoman Morgan Pumpa said relief was on its way for some, while others would have to wait longer for the cool change.
"The severe heatwave conditions in Queensland, NSW and parts of Western Australia are being caused by a high pressure system and we're awaiting that cold front," she told AAP.
"A trough moving through is going to bring some relief to parts of the south tomorrow."
A heatwave warning was also issued for WA, parts of NSW, Queensland and the Northern Territory.
Locally extreme heatwaves impacted the Pilbara and Gascoyne with some remote communities registering 47C.
Demand for electricity has increased as households attempt to keep cool and the Australian Energy Market Operator urged people to conserve energy where possible to reduce the pressure on the grid.
About 40,000 homes across Queensland were affected by power outages on Monday but Energy Minister Mick de Brenni said it wasn't due to a lack of energy supply.
"There was a storm that did roll through some suburbs, we saw 213,000 lightning strikes and the usual sorts of impacts of vegetation across powerlines," he said on Tuesday.
"The second reason was some heat impacts on localised hardware, so a combination of high demand and prolonged heat on some localised hardware saw that hardware trip to protect the system."
Ms Pumpa said people should reduce outdoor activity during the hottest parts of the day as much as possible, check in on vulnerable neighbours and keep an eye on their pets.
"Once we move up in that range of the severity of heatwaves, people do need to take extra actions to stay safe," she said.
