Former Sydney Swans player Troy Luff still remembers the green shade of the clouds he witnessed from the Sydney Cricket Ground, just moments before the noise began. It sounded like an avalanche getting closer and closer. Then, out of nowhere, giant clumps of ice the size of cricket balls, some even larger, blasted through roofs and windows and bounced off car bonnets at 200 kilometres per hour. More than 500,000 tonnes of ice — the equivalent of three large cruise ships — fell onto Sydney's southern, eastern and inner suburbs, leaving the city in tatters. The event, in 1999, became the costliest natural disaster in Australia's insurance history — a title it still holds to this day. But the Sydney hailstorm was more than just a once-in-a-lifetime disaster. It was a wake-up call, exposing how vulnerable our cities could be to extreme weather, becoming a transformative moment for the emergency services we know in Australia today. It also highlighted the immense costs of extreme weather — underscoring the financial risks insurers and communities continue to grapple with as climate change increases the severity and frequency of disasters. No warning about the 'mother of all storms' The storm caught the city by complete surprise, with no warning from the Bureau of Meteorology (BOM). "The storm was there, but I thought it was going to stay off the shore, but it just came inland, and before I could do anything, the phone started to ring and I was caught up with, you know, the reduced staff overnight, so we were too busy," BOM duty forecaster Evan Bathe said in an interview to the ABC the day after. The unusually intense and long-lasting supercell thunderstorm — the most dangerous kind there is — was later dubbed the "mother of all storms" by the State Emergency Services. From the ground of the SCG, Troy Luff — like many others across the city — ran for shelter, doing his best to avoid the missiles of ice that were pelting down on the oval. "There was only one player, Stefan Carey, he did cop one in the head and it did cut his head," he said. Once undercover, Luff remembers standing in shock — the noise deafening. "You couldn't talk to the guy next to you, it was so loud. There wasn't really any conversation at all," he said. The storm's destructive power left 500 people homeless. Fifty people suffered injuries and one person died due to a lightning strike. More than 24,000 homes and 70,000 vehicles were damaged. Many cars were not just dented, but left with huge holes through the windscreen and metal, as if someone had dropped a canon ball on them. All up, more than 130,000 people were impacted, due to collapsed sealings, smashed roof tiles and windows, according to Emergency Management Australia (EMA). The bill was enormous. The Insurance Council of Australia estimated it cost close to $9 billion in today's terms — far more than the 2022 floods in SE Queensland and NSW, which are estimated to have cost $6 billion. In the aftermath, "hail sales" became commonplace with Australians quick to turn the unfortunate circumstances into an opportunity for a bargain. "And a lot of [Sydney Swans] players, because at the time we were sponsored by City Ford, turned up in brand new, very dented Fords after that," Luff said. The mammoth clean-up The NSW State Emergency Services (SES) was completely overwhelmed and under-resourced, with the storm fundamentally changing the organisation as we know it today. Volunteers were responding to thousands of calls out of a small three-bedroom house. There were over 40,000 calls for assistance — a figure that still baffles Paul McQueen, who was a young volunteer at the time. Australia even had a shortage of tarpaulins at one point, so many were being used, according to Paul McQueen. The disaster sparked major criticism of emergency services, particularly the SES. People decried a lack of information about when homes would be fixed. Some said the army was called in too late. A review of the event found that would not have made a difference. Nevertheless, serious weaknesses were exposed. The organisation did not have a centralised phone number at the time. They were recording jobs by pen and paper. They didn't have the means or the media relationships in place to communicate with the public clearly. "We would literally be handing [volunteers] a pile of papers with job details and the requests from the assistance from the community and saying, you know, here's these 10 jobs, get through as many as you can and come back to us at the end of the day," he said. Six months later, permanent repair works were still being carried out. Storm a catalyst for change It was the biggest test the SES had ever faced. These days, our emergency services, including the SES, look very different from how they did in 1999. They now have far more advanced warning systems and public messaging in place and work together with other agencies in a much more coordinated way. While many of these changes are due to the technology, Paul McQueen says the hailstorm proved a catalyst for a lot of it. "I think that the interactions with the media, the public messaging that we do these days, there's some world-leading things that we really do," he said. A growing threat The event also rammed home how severe and costly the fallout from extreme weather events could be on our cities — an issue the insurance industry is grappling with to this day. It's not clear how this particular event affected insurance premiums. But the industry is keeping a close eye on hailstorms because one thing's for certain — they're expensive. In Australia, hailstorms are the second most costly natural peril for insurance companies, behind floods. These costs are only increasing as the population and wages grow. That's affecting insurance companies, and, ultimately, all of us. Sydney and Brisbane are particularly vulnerable to hail. There is also the question of climate change and future risks. A lack of data makes future projections of hail tricky. But what climate scientists do know is that, in general, a warmer atmosphere makes bigger hailstones more likely, even if they happen less often. This is something insurance companies are paying close attention to, according to Michael Hunneyball, the operations chief engineer for insurance company FM Global. "From our standpoint, it's a little bit of an unknown at the moment. "But I think when we look at how cities are developing in Australia, we know that hail storms [are] frequent enough anyway, they're going to be doing more damage because there's more buildings out there." Mr Hunneyball said it meant everyone needed to be thinking about extreme weather, and how they could better prepare for it. "We're looking at where are the most prone areas in Australia to large hail, and we've developed a map to actually show which parts of Australia are more prone to the larger hail," he said. "So, now we have this information, we can talk to clients, and when they're looking at developing in this area, we can work with them to choose better building products or more resilient solar panels that have been tested to be able to withstand larger hailstones."