How the record-breaking ‘heat dome’ enveloped Australia

The record-breaking heatwave scorching south-eastern Australia this week has fuelled deadly bushfires, filled skies with choking smoke and made temperature records tumble.

Described as a “heat dome” for its sheer persistence and super-heating qualities, the heatwave has had an effect akin to putting a lid on a boiling pot.

Four states have recorded persistent temperatures approaching 50 degrees, while Falls Creek ski village in Victoria recorded its first 30-degree day on Wednesday.

So how did the heat dome envelop Australia?

The wave of intense heat steadily swept across Australia – particularly inland areas – from the north-west of WA from January 19. On that day, the Pilbara region sweltered through a blistering 48-degree maximum temperatures, said Bureau of Meteorology senior meteorologist Angus Hines.

By January 20, Shark Bay in the Gascoyne region had peaked at 49.2 degrees.

“As we headed into the second half of last week and into the start of the long weekend, we saw the weather pattern shift a bit, and that meant the wind started to drag the very hot conditions, the very hot air which had been accumulating over the north-west, started to drag that eastwards,” Hines said.

By Friday, January 23, that heat was pushing in earnest from the north-west of the country into the interior of Western Australia before moving into parts of South Australia and the Northern Territory.

At Newhaven Wildlife Sanctuary in the NT, a tract of 262,000 hectares that sprawls around Wartikinpiri, staff are used to the heat.

But this summer has been particularly brutal.

In an area with a mean maximum temperature of 32.8 degrees, daytime temperatures have been above 40 degrees every day for the past month, and teams from the Newhaven Wildlife Sanctuary and Ngalurrtju Aboriginal Land Trust have responded to five wildfires since October.

“You don’t acclimate particularly well to 45 degrees,” sanctuary manager Mike Rawnsley said.

During the Australia Day long weekend, extreme heat that started in WA extended across the centre of Australia and towards the eastern seaboard.

“Temperatures really started to build throughout South Australia, and started to get warmer in Victoria and NSW as well – lots of places were into the low 40s then,” Hines said.

“And that heat has just continued to build and amplify and strengthen across those south-eastern areas.”

This week four states – SA, Victoria, NSW, and Queensland – recorded temperatures approaching 50 degrees, a phenomenon the Climate Council describes as a public health emergency.

“Heat is a silent killer,” climate councillor Dr Kate Charlesworth said.

“It has killed more Australians than all other extreme weather events combined – with more than 1000 lives taken during heatwaves between 2016 and 2019.”

On Tuesday, Victoria broke the record for the highest temperature recorded when Hopetoun and Walpeup hit 48.9 degrees.

In those Mallee towns, and in Ouyen, about an hour’s drive away, residents endured temperatures above 48 degrees. Businesses shut their doors and streets emptied.

When this masthead visited Ouyen, we fried an egg in the sun with resident Donald McGregor. It took less than half an hour.

In western NSW, Fowlers Gap reached 49.1 degrees, its hottest day on record. Road surfaces melted.

Stephen Mills, who works as a greenkeeper at the Lake Cargelligo Bowling Club, took shelter from the midday sun in front of a small fan in his shed.

But it was no relief from the heat itself; Mills said it could reach above 50 degrees inside the corrugated iron walls.

In Western Sydney, pensioner Gladys (who did not provide her surname) lives with disabilities, chronic pain and limited mobility.

Extreme heat renders her a prisoner in her own home.

“I can’t be in the lounge room to relax or watch television until well after dark because I feel faint and sick due to the radiant, permeating heat,” she said.

Renmark, in South Australia, took the dubious honour of being the hottest place in Australia – indeed, in the world – on Tuesday, recording a blistering top of 49.6 degrees.

Tuesday was a day of records: Victoria recorded its warmest ever temperature recorded (48.9 degrees), NSW reported the equal second-highest temperature recorded (49.2 degrees in Borrona Downs), and South Australia recorded the fourth-highest temperature recorded (49.5 in the shade in Ceduna).

The alpine areas of Falls Creek in Victoria and the Perisher Valley in NSW recorded their first days over 30 degrees on Wednesday.

This heatwave has been remarkable for its longevity and spread across the country. It has affected parts of every mainland state and territory, although it has been particularly persistent in south-eastern Australia.

Weatherzone forecaster Anthony Sharwood said a heat dome was “a slow-moving, large high-pressure system in the upper atmosphere which effectively traps and intensifies a hot air mass underneath it”.

“A common analogy used to describe the effects of such a system is that it’s like a lid on a pot which stops heat from escaping,” he said.

“Heat domes suppress the upward movement of air and therefore the formation of rain-bearing clouds. They also prevent other weather systems from intruding and disrupting the persistent heat.”

Climate scientists say the rapidly changing atmosphere will make heatwaves more common and more intense as global heating accelerates faster than predicted.

The European Centre for Medium-Range Weather Forecasts reported this month that last year was officially the planet’s third-warmest year on record, behind 2024 and 2023.

The world is on track to overshoot the Paris Agreement target to limit warming to 1.5 to 2 degrees above the pre-industrial average, scientists say, meaning societies must prepare for climate adaptation.

Hines said, locally, heatwave conditions would endure in western NSW, much of SA and northern Victoria until Sunday or even Monday.

“The heat is shifting out of the south coast … down through both Adelaide and Melbourne with milder days, as well as many other coastal locations,” he said. “But for those in the inland, there’s no respite at the moment.”

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