‘Bigger, more frequent’ hail forecast for Australian cities

Younger Aussies are being warned to expect bigger and more frequent hail into the future, with a new study revealing which cities are most at risk.

Younger generations of Australians are being warned to expect significantly larger and more frequent hail into the future with a new study revealing which cities are most at risk.

The paper from UNSW’s Dr Timothy Raupach and Dr Joanna Aldridge looked at the possible changes a 2.4 degree rise in global temperatures would have on Australian hailstorms from 2080-2100.

“Between (time periods), there were increases in seasonal hail days of 29 per cent around Sydney/Canberra and 15 per cent around Brisbane,” Dr Raupach told NewsWire.

Large hailstones outside Parliament House in Canberra after a 2020 storm. Picture: David Foote/ AUSPIC/DPS

“Mean hail size increased by 0.5mm around Melbourne, Sydney/Canberra, and Brisbane, while maximum hail size, important for damage potential, increased by 7.8mm around Melbourne and 3.9mm around Sydney/Canberra.”

Dr Raupach said any hail above two centimetres in diameter was considered damaging.

“Here we’re talking about very large hailstones, sort of five centimetres or even 10 centimetres,” Dr Raupach said.

“Those are kinds of hail that can punch through people’s roofs and cause their roof tiles to break and then you get flooding inside the house and of course they also can damage cars and be very dangerous for people as well. 


“Because the damage you get from a hailstorm correlates very closely with the size of the hailstones that are produced by that storm, it indicates that in those regions we would be looking at an increased damage risk.”

Maximum hail ball sizes are predicted to reach up to 10cm in diameter. Picture: Danni/Brisbane Weather

Data from the Insurance Council of Australia (ICA) shows hail is already one of Australia’s most costly natural disasters with the frozen water missiles responsible for more than 20 per cent of insurance losses in Australia from 1967 to 2023.

Hail is also not currently part of the building regulations Australian constructors are expected to adhere to, it’s a point Dr Raupach believes can be acted on now to strengthen our cities into the future.

“I think there’s room for discussions around how they could be built in because hail already – even without the future climate forecast – causes really significant damage,” he said.

“It’s a leading driver of insured losses year to year.

“So building in things like hail resilience into our building standards would be a really good way to start to strengthen our cities. And then we can also look at possible future changes as well.”

The paper projected reductions in damaging winds in proximity to hail for Melbourne, Sydney/Canberra and Perth. Picture: weather zone

Dr Raupach said the research was still in its early stages and further studies were needed to gain greater clarity and confidence in predictions.

“This is just one study, so it’s looking at it from one angle. It’s using one simulation and one model,” he said.

“Ideally, we’d have multiple simulations in what’s called an ensemble where you have lots of different simulations and you can look at how much they agree or disagree.”

For those who are confused how a rise in global temperatures equates to giant hail balls, Dr Raupach explained for every degree the atmosphere warms, it can hold 7 per cent more moisture.

This added moisture means more “fuel” for passing weather systems to draw on, when that weather system is a hail producing one it means larger and more damaging hail.

Originally published as ‘Bigger, more frequent’ hail forecast for Australian cities