What we’ve learned from the Sydney hailstorm of 1999

It started in the FM office kitchen, sparked by a casual mention of the 25th anniversary of the massive hailstorm that hit Sydney in 1999. “It’d be great to do a piece on what we’ve learned,” I said to Michael Hunneyball, my colleague and FM Chief Engineer. He responded with a wry smile, “We haven’t learned anything.” Ok, fuse lit.

The Sydney hailstorm of 1999 remains one of Australia’s most significant natural catastrophes. It was only surpassed in financial terms by the floods in New South Wales and Queensland in 2022. The Insurance Council of Australia (ICA) conducted a research project last year to assess the potential impact if such a storm were to occur today. The findings were staggering: The $3.26 billion damage bill from 1999 would balloon to over $8 billion.

Back in 1999, a colossal thunderstorm unleashed large hailstones, carving a path through Sydney’s wealthy eastern suburbs, including a direct hit on Kingsford Smith Airport. In the aftermath, a sea of blue tarpaulins covered roofs with holes punched through by the hail. The damage was extensive and indiscriminate, affecting homes, commercial buildings, and vehicles alike.

One of the most striking aspects of the storm was the lack of warning. “You don’t typically get a lot of warning for these kinds of events because they’re storm cells,” Hunneyball explained. Even today, weather forecasts might hint at potential hail, but the accuracy and lead time are often insufficient for meaningful preparation.

The reaction at the time was a mix of shock and resilience. “I’m sure it was a major surprise to a lot of people, just the amount of damage,” Hunneyball said. He compared it to the 2010 Melbourne Hailstorm, where the aftermath saw people driving around with dented cars for months due to insurance delays. The 1999 storm caused similar implications, with a significant strain on resources to repair the widespread damage.

Sydney is no stranger to hailstorms, but the 1999 event was exceptional in its severity. “It was just a bigger event than others,” Hunneyball noted. “The scale of damage was unprecedented.”

Reflecting on the broader implications, the 1999 hailstorm might have been the canary in the coal mine for the increasing frequency and intensity of extreme weather events linked to climate change. “It was probably more hail than a normal hailstorm but given where it hit—the most expensive area of Sydney—it was significant,” Hunneyball said.

Australia is the second-most affected country by hail in the world, trailing only the United States. This fact often surprises people, as hail isn’t typically associated with Australia. Yet the climatic conditions on the east coast of Australia are conducive to generating large hail, similar to the conditions in the central corridor of the United States.

In recent years, there has been a push to better understand and map hail risks in Australia. This effort was partly driven by the need to protect infrastructure like solar farms from hail damage. “We’ve been asking for better hail maps because we need a clearer differentiation of where the big hail is,” Hunneyball explained.

Interestingly, South America has recorded some of the largest hailstones on Earth, particularly in Argentina. Parts of Europe, such as Germany, and regions in South Africa also experience hail. However, the damage in these areas often goes unrecorded on a commercial property scale. In contrast, Australia’s heavily populated areas mean that hail damage is more likely to impact businesses and infrastructure significantly.

Is it just a catchy headline to say we haven’t learned anything? Hunneyball elaborated: “In a word, no. The construction of buildings has not changed to be more resilient to hail over that period of time.” Following the 1999 hailstorm, building codes in Australia were reviewed, but it was decided that the overall scope of risks was not significant enough to warrant changes. As a result, roofing and construction standards remain the same as they were in 1999.

Adding to the complexity, the widespread adoption of solar panels has introduced new vulnerabilities. “Solar panels weren’t being used in '99. Now they are, and they’re not resilient to hail either,” Hunneyball pointed out. The future of hail risk in Australia is likely to see increasing damage due to solar panels on roofs and solar farms. Without building resilience into this technology, the issues will persist.

So, what can be done? Hunneyball suggests that the solution lies in developing better products, such as thicker and more resilient glass for solar panels. Currently, solar panels are tested for hail resistance using 25mm hailstones, which is inadequate given the size of hail seen in places like Melbourne and Sydney. “We need glass that is thick enough or resilient enough to withstand bigger hail.” he emphasized.

“Australia is the second-most affected country by hail in the world, trailing only the United States.”

The push for these changes could come from the insurance industry, which often drives improvements by declining to insure substandard installations. However, government intervention could also play a crucial role, especially when considering the stability of the power grid during extreme weather events.

Interestingly, damaged solar panels can also pose a fire risk. If a panel is damaged but continues to generate power, it can create an electrical fault, potentially leading to fires. This adds another layer of urgency for more resilient solar technology.

Beyond solar panels, general building resilience remains a challenge. For example, the standard Colorbond metal roofs used in Australia are only 0.5mm thick, which is not sufficient to withstand large hail impacts. Thicker, more resilient materials could help, but the cost and practicality of such upgrades are significant considerations.

Windows present another weak point. “Windows in this country are shocking at the best of times,” Hunneyball remarked. Single glazing is still common in Australia, making windows highly susceptible to damage. In contrast, countries in North America or Europe use double or triple glazing to withstand extreme weather conditions. “You wouldn’t get a single glazed window on your house in Canada because you’d freeze,” Michael noted. Better windows, such as those made from tempered glass, could significantly reduce hail damage.

Lastly, walls also need consideration. Non-concrete wall systems can be vulnerable to hail falling at an angle, causing damage to both walls and windows. Testing and improving these systems for hail resilience is another step toward better overall building protection.

Twenty-five years on, the Sydney hailstorm of 1999 serves as a stark reminder of nature’s power and the ongoing challenges in predicting and mitigating such events. While we’ve made strides in understanding the risks, the unpredictability of these storms means that preparation and resilience remain crucial. Reflecting on the lessons—or lack thereof— it’s clear that while we may not have learned everything, the conversation about how to better prepare for and respond to such natural disasters is more important than ever.