Written by:
Sandro Kriesch
ARCAS Managing Director, Head of ILS
Sacha Collinson
ARCAS Analyst
Landon Damiao
Vice President, Catastrophe Advisory
Executive Summary
Severe convective storms (SCS) have emerged as a significant catastrophe peril in the United States. Although scientific studies indicate a declining long‑term frequency of stronger tornadoes, insured and economic losses from SCS have risen sharply. This divergence is driven primarily by structural exposure factors—population growth in hazard‑prone regions, rising property values, inflation‑driven repair costs, and increasing concentrations of insured assets across the broader “tornado alley.”
Over the past decade, SCS has accounted for half of global insured losses from secondary perils, with hail representing most of those losses[1]. In the United States, the frequency of loss‑generating SCS events has shown a persistent upward trend, and aggregate insured losses for the 2020–2024 period reached USD 200 billion—2.5 times higher than the preceding five‑year period. Extreme examples such as the 2011 outbreak year illustrate the potential for outsized tornado‑driven catastrophes, while the 2022 France hail season underscores the international dimensions of the peril.e
Geographic patterns are evolving as well: multiple studies reveal an eastward shift of tornado activity toward states such as Kentucky, Tennessee, Mississippi, and Alabama. While it is not a relocation of hazard, this shift has meaningful implications for regional insurers whose portfolios may be increasingly exposed.
At the same time, catastrophe modelling has undergone substantial refinement. Modern SCS models incorporate high‑resolution radar, advanced atmospheric reanalysis datasets, significantly expanded claims data, and improved vulnerability calibration. These advances have strengthened the credibility of both frequency–severity estimates and aggregate loss projections, enabling more accurate evaluation of low‑layer and earnings‑volatility risk.
Against this backdrop, catastrophe bonds have become an increasingly attractive risk‑transfer mechanism for SCS as shown later in the article. Investor portfolios tend to be less exposed to the U.S. Midwest than traditional reinsurers, resulting in lower capital costs and competitive pricing for SCS‑focused structures. Since 2017, SCS has featured in one‑quarter of total cat bond issuance, with strong growth in peril‑specific transactions, even as a standalone peril within Quercus II Re (2025). Modern structuring techniques have broadened access, allowing even smaller and mutual insurers to obtain cost‑efficient multiyear, fully collateralised protection.
In an environment characterized by rising exposure, heightened loss activity, and evolving hazard patterns, SCS‑focused cat bonds may offer a compelling opportunity for insurers and ILS investors alike. Enhanced modelling capabilities, stronger empirical loss experience, and increasing market acceptance all support the development of innovative structures designed to manage volatility from frequent, non‑peak‑peril events. For U.S. regional insurers in particular, catastrophe bonds provide a materially valuable complement to traditional reinsurance—strengthening resilience, stabilising earnings, and supporting sustainable underwriting performance.