Brisbane is heading to a maximum temperature of 35 degrees Celsius today and Ipswich 37C as south-east Queensland endures another heatwave.
It will also be scorching again tomorrow with Brisbane expected to reach 35C and Ipswich 38C.
Bureau of Meteorology senior meteorologist Harry Clark said that was 6C and 9C above average for March and just a few degrees short of records.
In New South Wales, maximums will be as much as 10C above average during the next four days, reaching the mid-30s near the coast and exceeding 40C in the far west.
Sydney’s maximums have so far averaged 29C this month, 4C above the long-term average and on track to be the hottest March on record.
The high temperatures have been classified as a low-intensity heatwave across parts of South East Queensland, and eastern New South Wales.
Mr Clark said it had been caused by slack winds across central and northern Australia for the last week that have not flushed out a hot air mass.
That air mass has now stagnated.
"The air is stewing in place," Mr Clark said.
Furthermore, a northerly wind is dragging up the warmer air from the interior, towards coastal communities.
The temperatures today and tomorrow are a few degrees shy of the March records.
In 2007, Brisbane got to 37.9C and in 2019, Ipswich hit 41.3C.
Mr Clark said the worst of the heat will be done by Saturday with ocean breezes coming onshore to give some relief and maximum temperatures coming down to the low and mid 30s.
But that would still be above average for March.
Mr Clark said there would be no afternoon relief from storms over the coming days, but there could be "significant" showers by Tuesday.
Extreme fire danger for NSW
Despite the enduring heat, the fire danger for South East Queensland has been set at moderate.
Mr Clark said there was reduced risk because it was not windy and there had been recent rain, with the ground still a little wet.
However, there is a high fire danger on the Darling Downs, west of Brisbane tomorrow.
There was also a high fire danger for large parts of NSW today where hot, dry and windy weather had increased the fire risk.
There was a risk of extreme fire danger in the Central and Southern Ranges, where a total fire ban was in place.
The ABC's meteorologist Thomas Saunders said conditions could ease by tomorrow.
"Thankfully through the heatwave, winds are only expected to reach fresh or strong speeds during Thursday which should keep fire dangers below extreme from Friday to Sunday," he said.
