Millions of Australians in the country’s largest cities could be facing a future of giant, more intense hailstorms, according to a new study.

Sydney, Canberra, Melbourne, and Perth are all in the firing line, according to the research from the University of NSW’s Sydney’s Institute for Climate Risk and Response.

The study found that climate change could bring more damaging hailstorms as the globe heats up.

In analysing simulations of weather in a warmer world, “we’re seeing an increase in hail size over some capital cities”, study lead author Dr Tim Raupach said.

However, other cities such as Adelaide did not show major changes in the simulations.

“More research is needed to better address the complexities in modelling hail,” Raupach said.

Hailstorms were responsible for more than 20 per cent of insured losses in Australia from 1967 to 2023.

The damage is largely driven by the size of hailstones, with the record in Australia standing at about 16cm across for a stone found near Mackay, Queensland – more than twice the size of a cricket ball.

Raupach said more intense storms in the future could increase the chances of large-diameter hail.

“We looked at changes in hailstone size between simulations of historical and future periods,” he said.

“And we can see increases in hail size produced by the model around Sydney, Canberra, Melbourne and Perth.

“For example, in past simulations, very large, 10 cm hailstones were expected once every 20 years around Melbourne. But in a warmer future, it’s once every three years.”

Despite being made of ice, hailstones rely on warmth for their formation.

In a thunderstorm, strong winds – updrafts – carry moisture high up into the atmosphere, where it freezes. These ice particles – known as ‘hail embryos’ – pick up supercooled water as they circulate through the storm cloud.

To grow large hailstones, the storm cloud needs to be tall, with lots of energy to keep the stone suspended long enough to gather layers of ice.

While hail can fall anywhere in Australia, certain regions are particularly exposed.

“The main region is the East Coast from a bit north of Brisbane to a bit south of Sydney,” Raupach said.

One of the major concerns about an increase in hail in that heavily-populated area, is the vulnerability of solar panels – though Raupach said this should not deter investment in renewables.

“We should also think about how to strengthen our cities to resist hail damage, especially if hailstone size is increasing with climate change,” he said.

But in the meantime, Australians should become more acquainted with hail preparation.

“To be protected from hail you can move undercover, move your car undercover, have good insurance and have strong roof tiles,” Raupach said. He says some farmers use hail nets.

QBE Insurance’s Dr Joanna Aldridge, co-author of the study, warned that Australian building standards don’t include hail resistance.

This left many properties “vulnerable”, she said.

If Australians need to take steps in the short term, Raupach also urged long-term action, both to reduce greenhouse gas emissions and to further the study of future hail trends and how they could affect urban environments in particular.

“It’s very early days, but maybe one day we could design cities with a reduced storm risk,” he said.