Scientists say summer of weather whiplash points to driving force of climate change

Scientists are warning this summer's sharp swings from record heat to torrential rain illustrate how climate change is becoming a dominant driving force in our weather.

Over the past few months, multiple parts of the country have lurched from extreme heat to flooding — sometimes in a matter of weeks — in a summer that has been described as one of "breakneck climate whiplash" by the Climate Council.

Making it more unusual, according to meteorologist and climate councillor Andrew Watkins, is that many of the extreme heat records have occurred despite the presence of a weak La Niña — which typically brings cooler, wetter conditions to large parts of Australia.

He said it points to a new reality where once reliable drivers of weather are now being overpowered by human influence.

"We are seeing records occur when we wouldn't really expect to see them."

Climate whiplash affected every state

In a new report by the Climate Council, which catalogues the summer's extreme events and their toll, examples of weather flipping from one extreme to another can be seen in nearly every state and territory.

One of the most stark examples of climate whiplash over recent months was in south-eastern Australia, where communities went from extreme heat and catastrophic fire warnings to flash flooding and back again in the space of just one month.

This timeline shows how that played out for Victoria's Otway Ranges in the state's south-west.

In early to mid-January, the region swung from extreme heat and fire weather warnings to dangerous flash flooding on the Great Ocean Road five days later.

By the end of the month, it was back to extreme heat again as another major heatwave, of even higher temperatures, unfolded across the south-east of the country.

Before: A fire burns close to a home near Gellibrand in Victoria's Otways in late January 2026. . After: Less than a fortnight before the fires, cars were swept into the ocean during flash flooding nearby on the Great Ocean Road.  . .

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Mildura, in northern Victoria, was another town that experienced intense flips from extreme heat to rain.

At the start of March, flash flooding prompted over 100 calls for flood assistance after its wettest day on record.

The deluge came after a summer of record-breaking heat and bone-dry conditions.

In January, the town experienced as many days above 45 degrees Celsius as in the half-century before 2000.

In South Australia, Maree — in the state's far north — jumped from five days in a row above 48C in January, and no rain for over a month, to being cut off from flooding when the region received 10 times its average February rainfall in just a couple of days.

In Western Australia, critical transport lines were disrupted between Perth and the eastern states on multiple occasions.

First, by a bushfire near Caigun, which caused the main highway to be closed. Then, just a day later, by floods in the wake of Tropical Cyclone Luana.

Meanwhile, in Queensland, there was intense summer rainfall, with some towns in the state's west recording their average annual rainfall within the first five weeks of 2026.

In more recent weeks, towns such as Longreach and Bundaberg have been inundated as vast amounts of water make their way through the outback river systems, impacting homes and businesses.

"These changes that we're seeing now, this sort of supercharged weather that we're seeing really isn't possible without a century of global warming and those extra fossil fuels or extra CO2 that we've put into the atmosphere," Dr Watkins said.

Whiplash summers becoming more intense

Extreme events aren't unusual in a vast country like Australia, particularly during the "high-risk weather season" of summer.

But University of Melbourne climate scientist Linden Ashcroft, who specialises in historical climatology, said what stood out this year was the scale of the extremes.

Data from the Bureau of Meteorology (BOM) shows this summer, 60 all-time heat records tumbled, and February's overall rainfall neared all-time records for some states.

Port Augusta, in South Australia, is now the most southern place on Earth to have recorded a 50C day, according to the Climate Council report.

Dr Ashcroft said that record, in particular, "blew her away".

"I work with historical weather observation … and I know that we are a land of extremes," she said.

"I haven't seen a 50C in any of my historical observations.

She said the weather that had always been part of Australia's summer was now amplified.

"What we're seeing now, and actually the research backs that up, is that these swings, these whiplash events are becoming more extreme in a supercharged atmosphere."

La Niña fails to temper extremes

Another stand-out feature of summer noted by climate scientists, including Dr Ashcroft and Dr Watkins, is the lack of influence from the weak La Niña event, which was also present.

La Niña is a major climate driver in Australia, typically linked to cooler, wetter weather for most of the country, quite different to what was seen this summer.

"So we have these extremes of temperature in a period where you typically expect temperatures to be milder rather than necessarily as extremely hot," Dr Watkins said.

"And we also have very dry conditions [at times]. So parts of Southern Australia had a relatively dry December and also January as well."

Dr Watkins said it showed how human-driven warming was increasingly overpowering the once reliable natural climate drivers that once shaped Australia's seasons.

"Our climate is becoming more complex," he said.

The "atypical" nature of this year's La Niña adds to a growing list of examples of the major climate driver not having the impact it once might have.

Last year, the BOM announced it was "retiring" its cyclone outlook because the model — which was based on the historical relationship between El Niño and La Niña and the number of cyclones — was not getting it right enough of the time.

In late 2024, the weather agency also decided to drop its routine "watch" and "alert" dials for La Niña and El Niño to tone down the emphasis on the role of individual drivers, following a wetter-than-usual El Niño summer.

Australia counts costs in extremes

The weather extremes witnessed this summer can be obscured in overall seasonal data.

Overall, the 2025/26 summer ranked as the eighth warmest on record and the 12th wettest.

But the finer details reveal the remarkable and extreme events that occurred within the season.

Dr Ashcroft said it's these kinds of extremes — not averages — that are felt by communities.

"Extremes is where the rubber hits the road from a climate change point of view," she said.

According to the Climate Council report, annual disaster costs per Australian have risen by 200 per cent since the 1980s.

Insurance premiums are up 51 per cent in five years, even for households that aren't directly affected by fire, floods or storms.

She said it was crucial to adapt to the new reality where extreme weather events were not isolated incidents.

But she said the most pressing theme was that weather extremes, as seen this summer, were likely to worsen the longer emissions were added to the atmosphere.

"All of these components can happen in an Australian climate without human-induced climate change, but to have human-induced climate change on top just means that they're more likely and when they happen, they're more intense."