Thousands across Victoria are without power as the state swelters, with just one day of respite from the hot weather before the mercury soars again on Friday.
Melbourne reached a scorching 40.1C just after 4pm on Wednesday, while the state's northwest cracked the mid-40s as Walpeup hit 44.3C.
Power went out out for about 3000 PowerCor customers in Werribee and surrounding suburbs about 4pm on Wednesday.
Another 1400 Ausnet customers in Alexandra suffered a two-hour power outage from 5pm to 7pm on Wednesday.
Across Victoria, power company outage maps showed more than 3000 customers were still affected by 7pm.
The Bureau of Meteorology forecast a southerly wind change to bring temperatures down overnight, with milder conditions across southern areas forecast for Thursday.
"It's not a real strong change, it's not one of those days where we'll get a sudden drop of 10 or 15 degrees in the temperature but more of a gradual ease in the temperature overnight," senior meteorologist Dean Stewart said.
It will stay hot in the north, with a total fire ban in place for the region.
The mild weather will be short-lived, as Friday's maximum temperature in Melbourne was upgraded to 43C.
"Northerly winds are going to bring that very hot air over the north right down across the state right down to the coast, so 43C in the city some suburbs even nudging 44C," Mr Stewart said.
Melbourne could on Friday record its hottest December day, with the record of 43.7C set in 1876.
A total fire ban has been declared for all of Victoria on Friday.
"We urge all Victorians to be aware that fires can happen anywhere and without warning, and to make their plans accordingly," Response Controller Gavin Freeman said in a statement.
"Fire agency crews are well prepared and it's extremely important that the community is also prepared, not only for the next couple of days, but for the months to come".
As the mercury climbs, authorities are warning people to prepare for the hot weather.
"With dry, windy and close to 40 degree days predicted, we want everyone to be alert to the symptoms of heat-related illnesses," Ambulance Victoria's Justin Dunlop said.
Residents are urged to check on their neighbours, infants, the elderly and expectant mothers who are some of the most vulnerable in this weather.
Australian Associated Press