An extreme fire warning has been issued for the Mallee and Wimmera districts in Victoria, with the mercury set to hit more than 40 degrees.
Bureau of Meteorology senior forecaster Callum Stuart said Mildura and Hopetoun, in the state's far north-west, had already hit 38 degrees on Sunday.
A total fire ban has been declared in much of Victoria's northwest.
Mr Stuart encouraged campers along the Murray River to take heed of fire warnings given the strong potential for ignition.
"With that heat and dry air coming down from the north, and some pretty strong northerly winds as well, we're seeing extreme fire danger ratings," he said.
Mr Stuart also said a severe wind warning remained in place for damaging winds, with Mount William, in Victoria's north-west, recording gusts of up to 98 km/h on Sunday.
The winds would likely hit Melbourne about 4pm on Sunday, he said, as a cold front approached from the state's south-west.
"The wind is starting to pick up in the metropolitan area as we speak," Mr Stuart said.
"It will be quite a sharp change around the south-west with temperatures cooling off nicely around it."
Country Fire Authority chief officer Jason Heffernan says the conditions have made a total fire ban necessary for four districts until 11.59pm on Sunday.
"The Mallee, Wimmera, North Central and Northern Country will experience elevated dangerous fire conditions and as a result, we have declared a Total Fire Ban across the four districts," Mr Heffernan said in a statement.
He said the ban imposed strict rules on the use of farm machinery, chainsaws and lawnwomers and he urged campers not to light campfires.
"We would really urge people not to light one earlier in the night either or in other areas of Victoria," he said.
Mr Heffernan said campfires lit in recent days needed to be properly extinguished to avoid flare-ups.
