Emergency services authorities are bracing for a searing heatwave and dry thunderstorms that have the potential to spark new blazes and fan flames on existing fire fronts.
The mercury is set to jump into the high 30Cs and low 40Cs across Victoria over the coming days, posing fresh challenges for fires still burning in the west of the state.
Crews were still battling multiple fronts on Sunday, though Victorian Emergency Management Commissioner Rick Nugent said firefighters had managed to contain the blaze in the Little Desert National Park.
"Our firefighters did an incredible job to fight those fires," he said.
Watch and act warnings remained in place for both the northern and southern Grampians fires, with crews working hard to contain blazes and prevent damage to the national park home to about 200 Indigenous rock art sites.
Crews have been scrambling to take advantage of benign weather to backburn ahead of scorching temperatures.
Mr Nugent warned the looming heatwave would bring potential for dry lightning and little hope of significant rain.
"The heat may also impact our current fires in the landscape and make new fires easier to start and spread," Mr Nugent said on Saturday, with the west and centre of the state most at risk of blazes sparked by dry lightning.
Bureau of Meteorology senior meteorologist Kevin Parkyn said the heatwave was caused by a "blocking pattern", involving a slow-moving high pressure system causing the recirculation of hot air from continental Australia over Victoria.
Maximum temperatures above 40C can be expected in some parts of the state and Melbourne is on track for three days in a row above 37C.
"We're looking at more than 10 years ago to see a heatwave of similar significance," Mr Parkyn said.
While much of the thunderstorm activity in coming days would be dry, the meteorologist said localised heavy rain was possible in the Grampians and other parts of the state on Sunday afternoon.
Relief from the heat can be expected by Tuesday, with cooler air forecast to sweep across the state and drop temperatures.
Country Fire Authority chief officer Jason Heffernan said the heat and unstable air brought fresh risks for crews and communities if blazes became big enough to generate their own fire thunderstorm.
"What it does mean is it generates its own lightning and its own windstorm ahead of the main fire front," he explained.
Mr Heffernan urged Victorians to stay abreast of emergency updates and be prepared.
Trish Ravenhall, who had to evacuate when fire threatened her community in Halls Gap, warned others to have a bushfire plan and kit ready with the necessities.
"In hindsight, we should have been more prepared before we got the evacuation message, with an emergency kit ready to go," she said.
In their haste, the family later realised they had forgotten several essential items.
"Do it not just for yourself but for your family, your neighbours and the emergency services, who are there to protect us," she said.
