Mapping the Growing Threat of Hail

Hail is a unique natural hazard: sudden, localized and often dismissed as a cosmetic nuisance until it becomes an operational problem—punctured roofs, cracked skylights, smashed glazing, dented rooftop equipment or compromised solar panels written off in an afternoon.

FM’s new Worldwide Hail Hazard Map serves as a reminder that hail is not a regional quirk but a global exposure, surfacing in places not traditionally thought of as hail prone.

FM’s map takes a more nuanced approach to assessing the hail threat: Don’t just count hail days, measure what matters to property. FM’s model combines more than 500,000 ground-based hail observations from 1955 to 2024 with reanalysis and satellite datasets, using a machine-learning framework to link hail occurrence and intensity to the atmospheric environments that produce it. Unlike many conventional maps that emphasize frequency alone, FM’s map provides insight into hailstone size and kinetic energy—a more direct proxy for structural damage. In practice, it’s the difference between “this happens here sometimes” and “this can break your roof.”

Why now? Because the financial alarm has become difficult to ignore.

Consensus among experts is clear: Severe thunderstorms—or severe convective storms—have emerged as a main driver of rising insured losses, with vulnerability to hail damage contributing to the shift. In the first half of 2024, industry sources estimate that insured losses from severe thunderstorms totaled US$42 billion globally. They note that these storms accounted for 70% of global insured natural catastrophe losses in that period. The same storyline runs through 2023: Global insured losses from severe convective storms reached new highs, with the United States dominating the totals.

“The trouble with hail is that it behaves like a surprise even when it shouldn’t,” notes Mike Hunneyball, FM’s Melbourne-based operations chief engineer and hail expert. It’s not only about where the hazard exists but about where properties are not designed for it. Roofs are often value engineered—i.e., built to minimum performance requirements—while facades are typically chosen for aesthetics. Rooftop installations are often affixed as though the only weather they’ll face is rain. The main vulnerabilities are clear: building envelopes—including roofs and facades—along with glazing, yard storage, and roof-mounted equipment like HVAC systems and solar panels. In other words, Hunneyball adds, “The built environment we’ve been enthusiastically modernizing is also the built environment that hail enjoys rearranging.”

A quick tour of hail, with stops in the places that still look surprised

Start with the obvious: North America. Hail has long been a line item in U.S. risk management, but the rising concern is scale. Swiss Re describes the recurrence of multibillion-dollar loss events from severe thunderstorms as increasingly plausible, driven by a mix of growing exposure through increased development, higher property values and the vulnerability of insured property to hail. Even the long-running public loss record hints at the size of the category: NOAA’s archived “billion-dollar disasters” dataset lists 203 severe storm events from 1980–2024, with total costs of roughly US$514.4 billion (CPI-adjusted).

Now consider a continent not traditionally thought of as prone to hail: South America. A major recent global climatology of very large hail (>5 cm) identifies northern Argentina as a world hotspot, followed by the tri-border region around Uruguay, Paraguay and southern Brazil. This is where the “hail where you’d least expect it” hook gets serious: If the mental map of hail remains Colorado-to-Texas, then Córdoba or Rosario could come as a surprise—not because hail is unknown there, but because global portfolios sometimes treat it as an agricultural inconvenience rather than a property or business continuity hazard.

Europe is the quieter plot twist, largely because the trend is moving faster than the stereotype. Nature Geoscience research notes that severe hailstorms are increasing most rapidly in Europe, and highlights hotspots near mountain ranges: northeastern Spain, southwestern France and northern Italy. The study notes that severe convective storm losses are growing fastest in Europe, with Italy’s 2023 hail incidents acting as an uncomfortable case study in concentration risk. If you have operations in and around the Po Valley—the logistics belts feeding Milan, Verona and the manufacturing towns in between—European hail should no longer be filed under “car damage.”

Australia needs no convincing, but international stakeholders often do. The 1999 Sydney hailstorm remains a sharp reference point: The Australian Disaster Resilience Knowledge Hub recorded AUD$1.70 billion in insured losses from the storm, with widespread urban damage . If Sydney’s 1999 hailstorm were to replay today, it would strike a very different city from a construction and asset exposure perspective. In the past 25 years, Australia has installed more than four million rooftop solar systems, most of them on homes and commercial buildings that did not exist—or did not carry photovoltaic panels—in 1999. The Insurance Council of Australia has estimated that the insured cost of a like for like event would rise from AUD$1.70 billion in 1999 to around AUD$8.8 billion today, purely on changes in values and density. Add millions of exposed glass fronted solar modules to roofs across Sydney’s eastern, inner west and southern suburbs—assets known to be vulnerable to large hail—and the damage profile becomes significantly worse.

That is hail’s lesson in one line: Hazard plus density plus vulnerability turns an afternoon storm into a capital event.

Asia is best handled with nuance: Very large hail is generally less frequent than in global hotspots, according to global climatology, but “less frequent” is not “never.” FM’s own guidance captures the operational risk neatly. In markets where hail is rare, buildings are typically not designed with hail impact in mind—exactly the sort of low-frequency hazard that produces a surprise when it arrives. For a global portfolio, that’s the real danger: not the hazard you know, but the hazard you have architected out of your imagination.

What makes the FM Worldwide Hail Hazard Map worth paying attention to

“The map’s quiet strength is standardization,” says FM’s Hunneyball. “Until now, FM hail hazard mapping was limited to the United States and Australia. The new model extends the analysis globally using combined observations and physics-based modeling approaches.”

It categorizes risk into three zones—Moderate, Severe and Very Severe Hail—defined by kinetic-energy thresholds, aligned to established FM criteria (including a 15-year mean recurrence interval and assumed hail density). For risk leaders, that provides a single vocabulary for sites that sit in very different meteorological cultures—an antidote to the “local lore” problem.

Hunneyball adds that “lore is where hail thrives” since local memory is often shaped by what people have personally seen. “In Milan, a summer hail week now feels plausible; in Singapore it still feels like a curiosity; in Sydney, it’s an old story that can suddenly become new again.”

The discipline of the map is that it doesn’t know what anyone remembers. It cares what the data and the atmospheric environments suggest about hazard and damage potential.

A short forecast, and a longer warning

The latest global research suggests regional trends diverge: Europe shows the sharpest increase in very large hail frequency in the global analysis, while other regions vary, and losses rise through different mechanisms. Insurers, meanwhile, are clear-eyed about the direction of travel on losses. Experts point to exposure growth, vulnerability and the likelihood that multibillion-dollar severe thunderstorm events will become more common. Put together, the sensible conclusion is not “hail everywhere, all the time” but “hail in more board discussions than before.”

A useful mental model is this: Hail is the peril that targets modernity. Expansive glazing, lightweight roof systems, solar installations and outdoor storage are signatures of efficient, contemporary facilities. They are also plausible points of failure. The strategic response is less about drama and more about governance: Adopt a consistent hazard layer, specify materials and systems for impact resistance where it matters and stop treating “rare” as a synonym for “irrelevant.”

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