Hundreds of firefighters battled more than 100 wildfires across southern Australia as temperatures pushed above 40 degrees C (104 degrees F), the Australian Broadcasting Corp. reported.
A 41,000-hectare bushfire in Victoria's Grampians national park raised concern for firefighters by causing a nearly 7 1/2-mile convection column that produced thunderstorms and lightning.
Officials confirmed a woman died in the Grampians fire and at least two homes were destroyed in South Australia northeast of Adelaide.
Fire officials said they believe a dozen of the 68 fires in Victoria were deliberately set.
Victoria Police Chief Commissioner Ken Lay said detectives were investigating the suspected arsons.
"There are people out there at the moment that are deliberating lighting fires," he said.
Weather forecasters said a change in winds will bring gusts of 50 mph to 75 mph to the Grampians Friday.
Incident controller John Hanes told ABC strong winds are a concern for firefighters near the convection column that has spread embers and caused flare-ups over huge distances.
"The wind change will actually make that collapse, which will cause some erratic fire behavior for about an hour or so," Hanes said.