Temperatures in Canberra have soared to 44 degrees, the highest reading ever recorded in the city, beating a 1968 Canberra Airport record and a 1939 record.
The temperature reached Canberra's forecast maximum of 42 degrees at 12.46pm, and reached 42.2 at 1.17pm. It rose to 42.4 degrees at 1.26pm. By 1.31pm, it was 42.9 degrees. At 2.38pm 43.6 degrees was recorded.
It jumped again to 44 degrees at 4.08pm.
The temperature did not drop below 40 degrees until after 7pm.
A weather station located at Acton, which closed in December 1939, recorded a maximum temperature of 42.8 degrees on January 11, 1939.
The previous Canberra Airport record, set on February 1, 1968, was 42.2 degrees.
Bureau of Meteorology forecaster Abrar Shabren said temperatures had increased "very rapidly" in the last couple of hours with an upward trend likely for the rest of the afternoon.
Mr Shabren said dry conditions would remain in Canberra during the afternoon, with relative humidity very low.
He said winds would continue to increase into the mid afternoon.
"Winds start to decrease around the later part of the afternoon and into the evening so again there will still be westerly winds," he said.
"[A] cool change is moving across the NSW south-east coast, [but] will not have a great impact around Canberra," he said.
Mr Shabren said smoke from fires burning to Canberra's west, near Batlow and Tumut in the north and Adaminaby in the south, would continue to linger over the city.
Canberra's electricity network was operating within capacity, a spokeswoman for Evoenergy said.
Demand reached 550 megawatts at 2.45pm. Last year, system peak demand reached 657 megawatts after sustained heatwave conditions, she said.
The air quality index readings for Canberra's three monitoring stations remained above 400, twice the level considered hazardous.
Air quality index readings peaked about 5000 at the Monash station on Wednesday, about 25 times the threshold considered hazardous.
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