Records were broken after Yulara, near Uluru, recorded its hottest-ever Saturday in autumn as residents sweltered through a top of 45.3 degrees.
Oodnadatta in South Australia also had its hottest March day in 75 years after hitting a maximum temperature of 46.1 degrees.
There are heatwave warnings in place for the North Interior District, Kimberley, Pilbara, Gascoyne and South Interior Districts in WA.
The Bureau of Meteorology extended this warning until Tuesday.
All the Australian towns with record-breaking weather events
A severe heatwave warning was also issued for the NT regions of Daly, Tiwi, Gregory, Barkley, Simpson, Lasseter and Tanami Districts until mid next week.
The same goes for Queensland’s Gulf Country, North West and Channel Country Districts.
Temperatures are forecast to raise above 40 degrees over the next three days in large parts of these states.
Residents in these areas have been warned to stay inside, keep air conditioning and fans on and to look out for vulnerable people including the elderly and babies.
Today’s temperatures are also expected to reach as high as 34 degrees in some capital cities including Perth and Darwin.
Canberra is also in for an unusually hot March day with tops of 33 degrees, while Brisbane is set to reach a max of 30 degrees.
Sydney is a little cooler at 28 degrees and Melburnians will avoid most of the heat with tops of 21 degrees.
It will be a top of 27 degrees in Adelaide and just 19 in Hobart.