Authorities have urged residents in Victoria and South Australia to be vigilant on Tuesday with total fire bans in place across both states.
In Victoria, temperatures are tipped to hit the 40s and a severe fire danger warning issued for parts of the state.
The Country Fire Authority said total fire bans were in place in the Mallee, Wimmera and North Central districts.
The fire danger rating is severe for those areas – as well as the South West – and a very high rating is in place for the rest of the state.
CFA Chief Officer Steve Warrington said emergency services were on high alert and particularly focused in the north.
“Across the state, there is potential for fast-moving grass and forest fires,” Mr Warrington said in a statement.
“We’ve had a spate of grass fires in a number of areas, which have been challenging for firefighters given the high amount of grass and scrub growth.”
Melbourne is set to reach 38C, but a cool change is expected to sweep through by the evening, the Bureau of Meteorology says.
Other parts of the east coast are also set for a scorcher, with a top of 37C expected in Canberra and 40C in Western Sydney.
A high to very high fire danger rating has also been declared for most of New South Wales, according to the NSW Rural Fire Service.
Alert for South Australia
Meanwhile, hot winds and soaring temperatures have prompted total fire bans across much of South Australia, with severe bushfire risk declared in nine districts from the west coast to the upper southeast.
The Bureau of Meteorology says the mercury will hit 39C in Adelaide
with temperatures pushing into the low to mid 40s in some regional centres.
Tarcoola and Roxby Downs are forecast to be the hottest with 44C.
The Country Fire Service says recent rains across SA have done little to reduce the fire risk and people should take extra care.
“The declaration of total fire bans is driven by the dryness of the grasslands, along with predicted winds,” CFS state co-ordinator Leigh Miller said.
“Once grass is dry, further rains don’t affect the flammability – meaning there is still a high chance of fire.”
“Dry, warm and windy conditions mean any new growth from summer rains will soon dry out and add to the already inherent fire risk.”
Mr Miller said people following the Tour Down Under cycling race in the Adelaide Hills, which has its first stage on Tuesday, should avoid pulling over onto dry grass where a hot exhaust could spark a blaze.