Australia's heatwave smashes temperature records with some places nearing 50C

The Australian Open is off to a cooler start today after parts of Melbourne buckled under 45-degree heat yesterday, with a heatwave setting historic temperature records across the country's south-east.

But for south-eastern Australia's interior, the scorching temperatures are far from over.

For some, they're actually getting worse.

Parts of western New South Wales and Queensland are expected to near 50C today, on track to again break not just January records, but all-time local heat records.

Forecasts indicate, for areas away from the coast, that heat is set to linger until the weekend, in what the Bureau of Meteorology (BOM) has described as a "historic and record-breaking" burst of heat.

The only real difference from day to day will be where the highest temperatures — of 48C and 49C — are located.

"It's a very broad area of 40C-plus, but the highest temps of 48C-plus is what has sloshed around a bit," BOM's Jonathan How said.

"It was in northern Victoria and south-eastern SA on Tuesday. On Wednesday, it looks to be northern New South Wales into southern Queensland getting into 49C.

"Then, into Thursday, Friday, it sort of moves back into South Australia."

By Saturday, places like Wagga Wagga and Albury will have had seven consecutive days at or above 40C for the first time since 1939.

Fire danger also remains high to extreme through pockets of South Australia and Victoria today, and into tomorrow for New South Wales.

Has it ever hit 50C in Australia?

The continuation of extreme temperatures comes after numerous towns already broke their January and all-time records on Monday and yesterday, including a new state record for Victoria.

All-time records broken

Monday

• 49.5C at Ceduna, SA
• 48.6C at Wudinna, SA
• 47.3C at Trangie, NSW
• 46.1C at Dubbo, NSW

Tuesday

• 49.6C Renmark, SA
• 49.1C at Fowlers Gap, NSW
• 48.9C at Walpeup, now the hottest day ever recorded in Vic
• 48.9C at Hopetoun, the equal hottest day recorded in Vic
• 48.4C Mildura, Vic
• 48.3C Lameroo, SA
• 48.3C Ivanhoe, NSW
• 48.2C Loxton, SA
• 48.1C Longerenong, Vic
• 45.2C Point Cook, Vic
• 44.1C Melbourne Airport

If forecasts eventuate, yet more local records could be broken over the coming days.

Significant temperatures on Wednesday

• 49C at Thargomindah — very near Queensland's all-time high of 49.5C at Birdsville in 1972.
• 48C at Tibooburra, NSW
• 48C at Ivanhoe, NSW
• 48C at Wilcannia, NSW
• 47C at Moomba, SA
• 47C at Bourke, NSW

The temperatures experienced in this heatwave are still a way off Australia's all-time record of 50.7C, recorded at Oodnadatta in 1960 and Onslow in 2022.

Of course, measurements can only be taken where there are weather stations. So it's entirely possible that parts of the desert have been hotter — there's just no proof.

Extreme heat days increase

The places with the highest temperatures during this heatwave are no strangers to days above 40C.

But even for them, days this hot are exceptional.

"We often talk about the interior being the hottest place in the country, [or] the world at this time of year, but even these temperatures can challenge local residents who are pretty used to hot temperatures," Mr How said.

"We talk 'hot' thinking the low to mid 40s, not necessarily high 40s days on end."

A look back at the temperature history of several of the towns set to reach 45C during this event shows they have been happening far more frequently in recent years, however.

Mildura experienced just six individual days above 45C between 1946 and 2000.

This month, there have been four already.

The same can be said for Menindee, in New South Wales' Far West, where days of 45C or higher have gone from a rarity to something seen on average one to two times a year.

And for Hawker, in South Australia's Flinders Ranges, another town that could see six days in a row over 40C during this event.

Cooler change for the coast, but heat lingers inland

For southern coastal parts of SA and Victoria, things have cooled down today.

After parts of Melbourne reached 45C yesterday, the temperature is forecast to plunge to just 24C today.

The lack of "lasting" heat is why the area was not considered to be in a severe heatwave, despite the temperature being extreme.

This cool change for the coast has been summoned by a surface trough pushing through the south coastline, which is turning the winds around from the ocean.

But this cooler wind change isn't reaching far enough north to bring about relief beyond the coast.

Mr How said that wouldn't come about until Saturday.

"What we really want is a big cold front or a big surface trough to push through and finally flush out that heat, and we don't get that until Saturday," Mr How said.

Why is Australia in a heatwave?

The culprit for the extreme heat is once again the Pilbara region in north-west Western Australia, Australia's "heat engine".

Mr How said a hot air mass, which built across WA last week, moved into the east over the course of the weekend and has been "sitting in place with nowhere to go".

Also helping to set up the heatwave conditions is a cyclone off the north-west coast of WA, according to Mr How.

"Basically, they pump out heat at the top of the atmosphere, and push it downstream of the upper-atmospheric wave," Mr How said.

The same thing happened on Black Saturday in 2009, when Cyclone Freddy formed off the coast of WA.

Lack of monsoon spurs back-to-back heatwaves

The sweltering conditions mark the second major heatwave in a matter of weeks for south-eastern Australia — something Mr How said could be related to a lack of monsoonal activity in northern Australia.

"Heatwaves tend to follow a bit of a pattern across the country. They start in the west and then gradually move across, dissipate, and then build again," he said.

"We haven't had a big sort of monsoon flush out this year.

"So the lack of sort of monsoon activity in our region does mean that the heat has been building since the start of the month, and has [now] cycled back on that sort of two to three week time frame."

Heatwaves have always been a part of life in Australia's summers.

But the research shows they are also becoming far more common and more intense.

An analysis of the early January heatwave by international science group World Weather Attribution found the conditions seen in that event — which were not as extreme as the current heatwave — would have occurred once every 25 years before the pre-industrial era.

In today's climate, they return every five.

In other words, the last heatwave was five times more likely than it would have been without climate change.

"We know that we've always had heatwaves, but heatwaves are an extreme event. And by that, it means that they should be very rare," Australia National University climate scientist Sarah Perkins-Kirkpatrick said.