Hailstorms rank among the costliest natural catastrophes in Europe and have become a growing concern for insurers and society alike, with record-breaking events, such as the July 2023 storms in Northern Italy, causing over $3 billion in damage.[1],[2]
While the global rise in hail-related insured losses is primarily driven by increasing exposure and economic growth,[3] the severity and frequency of recent events have amplified concerns about how climate change may be influencing hail risk. Some studies suggest that hailstorms may produce larger hail more frequently in a warming climate, but the science remains far from settled.
A global review by Raupach et al. (2021)[4] summarized the state of knowledge: while small hail may become less common due to increased melting, large hail is expected to become more frequent, driven by stronger updrafts and greater atmospheric moisture. However, Raupach also highlighted that the trends are highly uncertain because changes in other factors influencing hail potential were less understood, such as storm types, storm frequencies, and aerosol concentrations.
This article explains what we currently know about hail trends in Europe under climate change, the important uncertainties that remain, and highlights three key insights that help guide our understanding.
01
One major challenge in understanding hail trends is that no single dataset captures all the key aspects of changing hail risk. Hail reports and insurance claims can offer some of the most direct measures of impact, but these are often sparse in rural areas or influenced by changes in exposure and reporting practices. As a result, researchers typically rely on proxy data to infer trends in hail occurrence and severity.
For example, lightning activity over the last two decades shows negligible or even negative trends over large parts of central Europe (Figure 1a).[5] However, less lightning does not necessarily mean lower hail risk: if individual thunderstorms become more intense, they could produce larger and more damaging hailstones even as storm frequency declines. Indeed, the high-density networks of hailpads in Northern Italy and Western France indicate a slight shift towards fewer but larger hailstones over a similar period.[8]
Another proxy indicator is the atmospheric environment of thunderstorms (Figure 1b),[6] which has become more supportive for large hail because a warmer atmosphere holds more moisture and generates stronger convective updrafts, both favoring larger hailstone formation. While this thermodynamic relationship is well understood,[9] proxies cannot fully represent the complex evolution of hailstorms, so additional approaches are needed to develop a robust understanding.
02
A more direct way to assess changes in hail risk is through high-resolution, “convection-permitting” climate model simulations that resolve individual storms in current and future climates. Studies focused on specific events or thunderstorm episodes consistently suggest that future hailstorms will feature stronger updrafts, greater water content, and thus produce larger hail on average.[10] [11]
Extended-period model simulations, although computationally expensive, are also more recently being conducted by several research groups. Preliminary results for Europe using sophisticated hail diagnostics show regionally varying trends, with some areas indicating an increase and others a decrease in hail risk (Figure 1c).[7],[12] A similar northeast-southwest dipole pattern has been found in the United States.[13]
This apparent divergence reflects the fact that hail risk is influenced by several competing factors. While stronger updrafts in a warmer climate favor larger hailstone growth within individual storms, changes in storm frequency, storm type, and melting processes can vary significantly across regions. Studies disagree on what factors are most important in what region. Moreover, while high-resolution models represent a major advance in hail research, they still have important limitations (see sidebar).
Nevertheless, what these models consistently show is that thunderstorm updrafts tend to strengthen, supporting greater hailstone growth.
03
Although overall trends are mixed, a clearer pattern is emerging in Europe's most hail-prone regions. A closer comparison across observations, proxy environments, and high-resolution simulations (Figure 1a-c) shows a broadly aligned signal.
Areas such as Northern Italy, Austria, and parts of Switzerland mostly exhibit increases in observed lightning activity, more hail-prone atmospheric environments, and a greater number of simulated hailstorms. In these regions, the intensification of thunderstorms and the growth of larger hailstones appear strong enough to offset any decreases in storm frequency, hail melting, or other limiting factors.
While hail trends elsewhere remain uncertain, for Europe’s hail hotspots, evidence points toward a rising and persistent threat.
Despite differences in methods, study periods, and proxy indicators, three broad insights are supported by recent research:
While confidence has grown, caution remains essential. Each research approach, whether observational, environmental, or modeling, carries important limitations, and none provide a complete picture on their own. Conclusions based on single studies or narrow time periods should be interpreted carefully.
The impact of hail trends will also depend on how hazard changes interact with exposure and vulnerability. Even if storms become less frequent overall, increased severity or economic growth can still drive higher insured losses. Therefore, the growing potential for more severe hail in already high-risk regions highlights the importance evaluating natural catastrophe models, insurance pricing, capital allocations and exposure aggregations to ensure they are fit for purpose, particularly in vulnerable markets like Northern Italy and Central Europe.
Collaboration between academia and industry, as was the basis for this article, remains crucial to closing knowledge gaps and has led to significant advances over the last decade. Research initiatives such as ICECHIP,[15] the first large field campaign on hail in over 40 years beginning in 2025, and the continued development of convection permitting models, are important steps toward building a clearer, more actionable picture of future hail hazard and vulnerability for risk managers.
