Millions of Victorians are in the grips of a three-day heatwave as tired crews try to tame raging fires following a night of wild weather.
Temperatures are expected to hover in the high 30s and low 40s for northwest, west, north, northeast and central parts of Victoria on Monday after a sweltering and stormy end to the weekend.
Severe thunderstorms swept across Geelong and Melbourne on Sunday night, bringing lightning, hail and damaging winds.
Power was cut to more than 38,000 customers across the state with unplanned outages as of 10.45pm Sunday.
But the storms are set to give way to blazing sunshine on Monday, with a forecast top of 39C for Melbourne and Bendigo, 38C for Geelong and 36C for Ballarat.
Meteorologists had predicted overnight minimums to stay in the mid to low 20s, heightening the chance of heat exhaustion.
To beat the heat, people should plan activities during the coolest part of the day, drink plenty of water, wear light and loose-fitting clothing and check on family, friends and neighbours.
"Extreme heat can be a killer," Premier Jacinta Allan told reporters on Sunday.
"That's why it's so important that we look after ourselves and look after each other."
Most at risk are those older than 65, babies and young children, pregnant women, people with acute and chronic health conditions and socially isolated individuals.
Severe heatwave warnings are also in place on Monday across the border in Adelaide and the SA regions of Riverland, Upper South East, Murraylands, Mount Lofty Ranges, Lower South East and the Mid North.
Sunday's hot conditions breathed new life into bushfires in the Grampians and Little Desert national parks, burning in Victoria's west since Australia Day.
Fire Forest Management Victoria sector commander Bec Luppino said the 40C heat was making life difficult for those on the ground.
"Your body temperature, your core temperature can get pretty warm," she said.
"It is tough, arduous work. We're working in extreme heat.
"We can sometimes get so caught up in what we're doing that we don't stop and take time to hydrate and refuel ourselves."
The Little Desert blaze was declared contained but broke away on Sunday afternoon, sparking a warning for people to evacuate the tiny town of Nurcoung.
An emergency warning was issued earlier for the small farming community of Mirranatwa as northerly winds picked up in the Grampians.
Those residents were advised to flee towards Dunkeld and take refuge at the Hamilton Performing Arts Centre or with family and friends outside the danger area.
