THE most extensive heatwave of the summer is building over inland Australia, setting up Sydney and much of the state for record-tilting heat over the coming weekend.
The extreme heat comes after Sydney mopped up for a second day following Tuesday's heavy rainfall. Damage from the event included a large sinkhole opening up in Point Piper, less than a kilometre from Prime Minister Malcolm Turnbull's house.
An area roughly the size of NSW will endure temperatures of 45 degrees or hotter on Saturday, elevating temperatures and fire risks across much of the nation's south east, the Bureau of Meteorology said.
For Sydney, wet weather on Tuesday and Wednesday will make way for steadily warmer conditions as the interior heat leaks eastwards.
A top of 29 degrees is predicted forSydney on Thursday before a trio of scorching days, with 36, 39, and 38 degrees forecast by the Bureau of Meteorology for Friday through to Sunday. The long-run average maximum forSydney in February is 25.8 degrees.
For places such as Penrith, Thursday's forecast top of 36 degrees will seem almost cool given what's expected after that. Friday to Sunday will see the mercury climb to 44-45 degrees.
"This could be the hottest three-day spell on record for the city," Graeme Brittain, a meteorologist with Weatherzone, said.
David Martin, a senior climatologist at the bureau, said it was rare for Sydney to record three days in a row of 35 degrees. The last time was in early January 1994.
The city has only had four such runs in its history, although it will be hard-pressed to beat the stretch of four days in January 1960, when each day topped 39 degrees and two of them were above 41 degrees.
For the western suburbs, the forecast for Friday to Sunday would also melt records. Penrith and Richmond have not had three consecutive days above 42 degrees in records going back 22 and 64 years, respectively, according to Weatherzone's Ben Domensino.
Richmond could lift its days this summer above 43 degrees to eight, smashing the old record of two days from 1958, 1979 and 2003.
Single-day February heat records to watch on the weekend will be 43.7 degrees at Richmond and 43.3 degrees in Bankstown, both set in 1977, 42.6 degrees at Sydney Airport reached in 1980 and the city's 42.1 degrees record set in 1926, Mr Domensino said.
Scorched earth
Even if Sydney misses out, the scale and longevity of the abnormal heat is likely to break heat records either for February, or for any month.
Three NSW towns are also in the running to beat the current record of 50 days above 35 degrees: Walgett, Moree and Mungindi, Dr Martin said.
The largest area of scorching conditions during the current heatwave may come on Saturday (see bureau chart below).
South Australia is also in the blistering bullseye, with Adelaide tipped to reached 42 degrees for a second day in a row on Thursday. Melbourne, too, will be very warm with 37 degrees forecast for Thursday.
A shortage of 100 megawatts of power capacity in South Australia prompted the Australian Energy Markets Operator to order SA Power Networks to introduce rolling blackouts on Wednesday evening.
For parts of eastern NSW, the coming heat burst will include regions of severe or even extreme heatwave conditions, the bureau said.
Sinkhole
The hot spell comes after several days of rain, some of it causing flash floods, in parts of Sydney.
Work crews continued to mop up on Wednesday, as well as deal with new problems such as a large sinkhole opening up in Point Piper near a vacant property.
Kristy Mirzikinian, who lives on Wentworth Street, said she could smell gas on Tuesday afternoon, and workmen came and were "banging around, breaking down the concrete" at the site.
She said she woke on Wednesday to discover the hole had opened up.
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