The state’s emergency management commissioner, Craig Lapsley, said hot temperatures had combined with dry weather, strong winds and a wind change to create dangerous conditions.
“It’s exactly what the forecast indicated and when we have fires running that’s obviously a problem for us,” he told a news conference.
About 400 homes lost power and 50 fires were reported across Victoria on Saturday, although many were small and were extinguished.
Emergency warnings were issued both in Victoria and in the nearby state of South Australia, where authorities advised residents of a rural area to seek shelter in buildings from an out-of-control fire.
Experts consider such a move to be safer than running the risk of getting trapped in the open if the fire suddenly changes direction.
Total fire bans took effect from midnight as Victoria, South Australia and Tasmania braced for dangerous fire conditions caused by temperatures exceeding 40 degrees Celsius (104°F).
The heat was strong enough to melt the bitumen on a 10-km (6-mile) stretch of freeway in Victoria, national broadcaster ABC News reported.
Australia is prone to deadly blazes, thanks to its combination of remote terrain, high summer temperatures and flammable eucalyptus bush.
In 2009, the worst bushfires on record destroyed thousands of homes in Victoria, killing 173 people and injuring 414 on a day the media dubbed “Black Saturday”.
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