Melbourne is sweating amid temperatures that have halted tennis matches, sparked bushfires and melted at least one Lindt chocolate in minutes.
A Melbourne man demonstrated the extreme temperatures by videoing chocolate melting on the pavement in under three minutes.
Melbourne is on course to sweat through a fourth day above 41 degrees today, the first time the city has recorded such prolonged heat in records dating back to the mid-1850s.
At the Australian Open tennis tournament, 970 spectators were treated for heat-related illnesses.
The city copped 43.9 degrees on Thursday, with heat so extreme the Australian Open tennis was halted for some matches for several hours.
More delays may happen today with the bureau tipping a high of 44 degrees for the city.
A new report on Australian cities has estimated that Melbourne had the highest annual average number of heat-related deaths, with about 200 a year. By comparison, the state's (Victoria) 2013 road toll was 242.
The number of heat-related deaths in Melbourne is expected to more than double by 2030.
During 2009's January heatwave, there were 374 more deaths across Victoria than would be expected for the week when comparing data over five years. The greatest number of deaths occurred in those aged 75 or older.
Adelaide's 44.2 degrees yesterday was the fourth in a row above 42 and a fifth is likely today. To the city's south-east, Mount Gambier broke its record maximum on Thursday.
The 44.1-degree reading beat the previous record by half a degree, said Blair Trewin, senior climatologist with the bureau.
Canberra, Melbourne and Adelaide each topped 40 degrees for a second day in a row for the first time in more than 70 years of records for all three cities, said Brett Dutschke, senior meteorologist at Weatherzone.
Both Adelaide's and Melbourne's maximums for today hinge on the timing of a cool change, with its arrival potentially adding or reducing the maximums by a couple of degrees, Dr Trewin said.
Residents in some Grampians and northern Grampians towns east of Melbourne have been told it is too late to leave their homes as an out-of-control blaze burns in a westerly direction.
Police confirmed a person has been killed in the Grampians bushfire.
The body was found at Roses Gap, 44km south-east of Horsham in the northern Grampians.
"The death is being treated as occuring as a result of the fires," Victoria Police said.
The Country Fire Authority issued an emergency warning just after 6am today for the towns of Wartook, Brimpaen, Heathvale and Laharum, urging all residents in the area to take shelter inside immediately and not leave their homes.
Winds are pushing the blaze in a westerly direction towards Wartook. It crossed the Northern Grampians Road between Heathvale and Wartook just after 6am on Friday. The Wartook Valley, between Flagstaff Track and Roses Gap, are affected by the blaze.
The towns of Glenisla, Cherrypool and Glenisla Crossing have also been warned about a 11,300 hectare fire heading in a south-westerly direction from Pohlners Road.
The CFA has advised communities to "watch and act" according to conditions.
Further north, fire authorities in New South Wales are gearing up for a tough few days, with the huge heatwave searing most of south-eastern Australia showing no real sign of abating until next week.
"We're still talking about Saturday" as the day of most risk, a spokesman for the Rural Fire Service said. "There are plenty of resources ready to go."
Total fire bans are in place for four regions in the state's south-east, with fire-danger ratings very high or high for most of NSW today.
No real relief was expected around most of Sydney until Monday.
The city's eastern suburbs and north shore will be areas of refuge from the heat, with maximums in the downtown and Terrey Hills regions reaching 29 degrees, the Bureau of Meteorology said.
Both areas can expect 31 on Saturday before a late cool change arrives.
The change is likely to be a modest one, with the city still expecting 27 on Sunday before Monday's maximum comes in at about 24.
There is little chance of significant rain at this point from the cooler conditions, said senior bureau forecaster, Peter Gajewski.
Before then, towns such as Penrith and Richmond can expect 39 degrees on Friday and similar conditions on Saturday.
Saturday will potentially be the most dangerous for fire, as stronger winds are forecast along with the cool change.
- Sydney Morning Herald
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