Totally Cooked: Episode 6 – Will hailstorms get worse with climate change?

Hailstorms might be brief, but their impacts aren’t. In this episode of Totally Cooked, hosts Sarah Perkins-Kirkpatrick, a Professor of Climate Science at the Australian National University, and Iain Strachan, a former journalist turned science communicator, are joined by Dr Tim Raupach of UNSW to explore how hail forms, why it causes so much damage, and what climate change means for its future.

We unpack the ingredients that make a hailstorm, why places like Canberra and the east coast of Australia are particularly at risk, and how hailstones grow into car-destroying chunks of ice. We also dive into forecasting challenges, billion-dollar insurance losses, and how new high-resolution climate models and machine learning are reshaping hail research.

Whether you’ve had a smashed windscreen, love watching storms roll in, or want to understand how even short-lived weather events are being reshaped by climate change, this episode will give you a fresh perspective on the hidden risks falling from the sky.

PS, if you finished Episode 5, you might have been expecting an El Niño episode this week. Don’t worry, we’ll be talking through everything ENSO with you soon enough.

Show Notes

In this episode, we look at:

• What hail is, how it forms, and why it’s different from other frozen precipitation
• The atmospheric conditions and storm dynamics that create large hailstones
• Why southeast Australia, especially the Brisbane-to-Sydney corridor, is a hail hotspot
• How climate change is making hail less frequent but more intense
• The billion-dollar impact of hail on homes, cars, and cities, including Australia’s costliest storm
• Why hail is notoriously hard to predict, and what radar can (and can’t) tell us
• The role of urban heat, aerosols, and wind shear in hailstorm development
• How AI and kilometre-scale climate models are transforming hail science
• What insurance companies care about (hint: it’s not heatwaves)
• Why hail remains one of the most uncertain and under-studied climate risks, and what researchers are doing about it

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Timestamps

00:00 – Opening Banter: Garages and Hail Warnings

The episode kicks off with light-hearted chat about parking habits, garage envy, and the local quirks of suburban living—before segueing into a more serious warning: hail is on the way. The hosts introduce themselves and the show, setting the tone for a deep dive into hailstorms and climate change.

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01:20 – What Is Hail?

The hosts reflect on their own (limited) understanding of hail before turning to expert guest Dr Tim Raupach. He defines hail in meteorological terms—solid ice larger than 0.5 cm falling from thunderstorms—and distinguishes it from similar phenomena like graupel. Hail forms when supercooled water freezes onto solid ice embryos inside storm clouds.

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04:30 – How Hailstones Grow

Tim explains the process of hailstone growth inside thunderstorms. Strong updrafts suspend small ice particles in supercooled regions of the cloud, allowing water to freeze in layers around them. The larger they get, the more likely they are to survive the fall to the ground—though some melt along the way.

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06:50 – Wet Growth vs Dry Growth

The conversation turns to two key processes: wet growth (when water stays liquid briefly and fills in gaps before freezing) and dry growth (when water freezes instantly on contact). These influence the shape and density of hailstones—and whether they’re smooth or jagged.

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08:45 – Studying Hail: From Lab to Sky

Understanding hail requires a combination of laboratory experiments, airborne observations, radar monitoring, and climate modelling. Tim shares stories of early aircraft-based research and the physical risks taken by storm-chasing scientists.

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11:30 – Where Does Hail Occur Most?

Hail is most common along the edges of the subtropics and into the mid-latitudes. In Australia, the hotspot stretches from Brisbane to south of Sydney, with Canberra also frequently hit. Globally, notable hail-prone regions include Alberta (Canada’s “hail alley”), the US Plains, Argentina, South Africa, and the foothills of the Alps.

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14:15 – Why Canberra Cops It

Sarah draws parallels between Canberra’s location at the foot of the Brindabella Ranges and hail-prone alpine regions overseas. Tim explains that terrain-induced uplift and surface heating are critical triggers for thunderstorm formation.

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15:20 – A Researcher’s Path to Hail

Tim shares how he started with rainfall microphysics and gradually moved into storm modelling and climate change impacts—eventually finding himself at the centre of hail research.

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17:10 – The Biggest Hailstones on Record

The largest recorded hailstone weighed about one kilogram and fell in Bangladesh in 1986. Tim explains the extreme updrafts needed to suspend such a massive stone inside a storm before it crashes to Earth.

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18:00 – Forecasting Hail: What’s Possible?

Radar provides the most accurate near-term forecasts, helping meteorologists track active storms in real time. But longer-range predictions are much harder—weather models can only suggest whether conditions are “storm-prone,” not whether hail will definitely fall in a specific location.

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20:00 – The Cost of Hailstorms

The Sydney hailstorm of 1999 remains Australia’s most expensive insured loss event on record. In 2020 alone, hailstorms in Canberra, Brisbane and Rockhampton caused billions in damage. Wealth, exposure, and location all influence the severity of economic loss.

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23:15 – Data Gaps and Modelling Challenges

Hailstorms are rare, highly localised, and short-lived—making it hard to gather long-term data. That lack of records makes climate-scale analysis difficult. Modelling hail also requires high-resolution simulations, which are computationally intensive and only recently becoming feasible.

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27:50 – Ultra-High Resolution and AI

Thanks to machine learning and increasingly powerful computers, kilometre-scale global climate models are now on the horizon. These models can finally resolve the kinds of convective storms that produce hail. It’s a game-changer for climate science.

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30:00 – Storm Chasers and Drones

International research groups are using drones and radar tracking to collect post-storm data, including drone photography over football fields to assess hailstone size and spread. Australia’s own Joshua Soderholm helped pioneer this technique at the Bureau of Meteorology.

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44:25 – How Climate Change Affects Hail

Tim breaks down the competing factors: warmer air holds more moisture and fuels stronger updrafts (which can produce larger hail), but increased melting and weaker wind shear may reduce how often hail reaches the ground. Overall, hail may become less frequent but more intense.

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49:00 – Future Research Directions

Key gaps remain in understanding aerosol interactions, modelling urban effects, and linking large-scale atmospheric patterns with hail events. Tim and his colleagues are exploring how cities might influence hail formation—and how better modelling could improve both projections and forecasting.

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56:30 – A New Era of Hail Science

Hail research is undergoing a revival. From once being seen as too small-scale to study, it’s now at the cutting edge of climate and weather modelling—thanks to rising risks, industry interest, and new computational tools. The coming decade could deliver breakthroughs in forecasting and risk reduction.

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59:45 – Final Reflections

The episode wraps with reflections on the science, surprises, and storytelling around hail. Everyone has a hail story, but few realise just how complex and costly it can be. From insurance to infrastructure, hail is more than just frozen rain, it’s a fast-moving threat in a warming world.

Further Reading

Allen, J. T., & Tippett, M. K. (2015). The characteristics of United States hail reports: 1955–2014. Electronic Journal of Severe Storms Meteorology, 10(3). https://doi.org/10.55599/ejssm.v10i3.60

Allen, J. T., Karoly, D. J., & Walsh, K. (2014a). Future Australian severe thunderstorm environments, Part I: A novel evaluation and climatology of convective parameters from two climate models for the late 20th century. Journal of Climate, 27, 3827–3868. https://doi.org/10.1175/JCLI-D-13-00425.1

Allen, J. T., Karoly, D. J., & Walsh, K. (2014b). Future Australian severe thunderstorm environments, Part II: The influence of a strongly warming climate on convective environments. Journal of Climate, 27, 3848–3868. https://doi.org/10.1175/JCLI-D-13-00426.1

Brook, J. P., Soderholm, J. S., Protat, A., McGowan, H., & Warren, R. A. (2023). A radar-based hail climatology of Australia. Monthly Weather Review, 152(2). https://journals.ametsoc.org/view/journals/mwre/152/2/MWR-D-23-0130.1.xml

Insurance Council of Australia (ICA). (2020). Catastrophe Summary: ACT, VIC, NSW hailstorm – January 2020. Insurance Council of Australia. https://www.insurancecouncil.com.au/

Prein, A. F., et al. (2017). Challenges and advances in convection-permitting climate modeling. Bulletin of the American Meteorological Society, 98(5), 1027–1030. https://doi.org/10.1175/BAMS-D-16-0263.1

Raupach, T. H., Soderholm, J. S., & Sherwood, S. C. (2023). Changes in hail hazard across Australia: 1979–2021. npj Climate and Atmospheric Science, 6, 143. https://doi.org/10.1038/s41612-023-00454-8

Raupach, T. H., Soderholm, J. S., Protat, A., & Sherwood, S. C. (2023). An improved instability–shear hail proxy for Australia. Monthly Weather Review, 151, 545–567. https://doi.org/10.1175/MWR-D-22-0127.1

Schuster, S. S., Blong, R. J., Leigh, R. J., & McAneney, K. J. (2005). Characteristics of the 14 April 1999 Sydney hailstorm based on ground observations, weather radar, insurance data and emergency calls. Natural Hazards and Earth System Sciences, 5, 613–620. https://doi.org/10.5194/nhess-5-613-2005

WMO. (2017). International Cloud Atlas – Hail. World Meteorological Organization. https://cloudatlas.wmo.int/en/hail.html

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Hosted by climate scientist Sarah Perkins-Kirkpatrick and science communicator Iain Strachan, Totally Cooked breaks down how human activity is changing the Earth’s systems—from our skies to our seas—and what we can do about it.

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