When Hail Rivals Hurricanes: Rebuilding the Property Rate for Convective Storms

Severe convective storms cost insurers roughly $208 billion across 2023, 2024, and 2025, with $176 billion of that landing in the United States, and in January 2026 Aon declared the peril the costliest insured hazard of the twenty-first century, ahead of tropical cyclones. Cotality's 2026 Severe Convective Storm Risk Report puts 43.5 million US properties, worth $17.84 trillion in reconstruction cost, at moderate or greater hail risk, and finds that a single severe hailstorm can now approach $30 billion in insured loss at a fifty-year return period. The peril that property actuaries spent two decades treating as noise around the hurricane signal has become the signal. The pricing problem is that the standard way of setting a property rate, trending a few years of the carrier's own loss experience, is structurally unable to keep up with it.

$208B

Global severe convective storm insured losses across 2023 to 2025, of which $176B was in the United States.

47%

Share of 2025 global natural-catastrophe insured losses caused by severe convective storms, about $60B.

$17.84T

Reconstruction cost value of the 43.5 million US properties Cotality rates at moderate or greater hail risk.

A Secondary Peril Reclassified as Primary

For most of the catastrophe-modeling era, the industry sorted perils into two tiers. Hurricanes and earthquakes were the primary perils: rare, modeled, and reinsured, with dedicated stochastic event sets and named layers in every property treaty. Hail, tornado, and straight-line wind were the secondary perils, lumped together as severe convective storm and treated as an attritional drag that the annual loss pick would absorb. That taxonomy no longer matches the loss data. Gallagher Re attributed about $60 billion, or 47 percent, of 2025 global natural-catastrophe insured losses to severe convective storms, and Aon put the 2025 SCS total near $61 billion, the third-highest on record. Over the three years through 2025 the peril has cost insurers $208 billion, and roughly 85 percent of that was American.

The reclassification is not only about totals. Cotality's 2026 report estimates that a single severe hailstorm striking a dense metropolitan area can approach $30 billion in insured loss at a fifty-year return period, a figure the firm places on the same scale as a Category 4 hurricane landfall. A peril capable of generating a hurricane-sized single-event loss is no longer a secondary peril by any underwriting definition, and pricing it as attritional noise systematically understates both the mean annual loss and the tail. The phrase the industry used to reach for, death by a thousand cuts, undersold the problem. Some of the cuts are now the size of a major hurricane.

Why Historical-Experience Ratemaking Underprices Hail

The standard property rate indication trends three to five years of the carrier's own loss experience, develops it to ultimate, and loads for expenses and profit. That method works when the underlying loss process is roughly stationary, so that recent history is a fair sample of next year's expectation. Severe convective storm violates the assumption in two directions at once. The frequency and severity of outbreaks are rising, driven by exposure growth in hail-prone metros and by a changing hazard, so the mean of the recent window is below the forward expectation. At the same time the year-to-year volatility is enormous, because whether a given carrier has a catastrophic year depends on whether a supercell happened to track over a city where it holds concentration, which is close to a coin flip on any single accident year.

Those two features combine into a credibility trap. A short experience window is both biased low, because the trend is upward, and statistically thin, because a handful of storm tracks dominate the sample. Adding more years to gain credibility reaches back into a period when the hazard and the exposure were materially different, so it trades sampling error for a stale mean. This is the same reason a few quiet hail years can lull a rate into inadequacy and a single bad year can appear to demand an implausible increase: the experience is describing storm tracks, not the underlying rate of risk. The defensible response is to stop estimating the SCS load from the carrier's loss triangle and to estimate it from a stochastic severe-convective-storm model that simulates tens of thousands of synthetic seasons against the actual exposure, the way hurricane and earthquake have been priced for years.

Building Exposure Into the Rate: Roof Age, Material, and Geography

A forward-looking SCS model is only as good as the exposure data it scores, and hail severity is unusually sensitive to building characteristics that traditional homeowners rating has carried loosely or not at all. The single largest driver of hail claim severity is the roof: its age, its covering material, and its condition. An asphalt-shingle roof near the end of its service life will total at a hailstone diameter that leaves a newer or impact-resistant roof cosmetically marked but functionally intact, and the difference between a repair and a full replacement is the difference between a small claim and a large one. Carriers that rate and underwrite on roof age and material, and that schedule actual cash value rather than replacement cost on older roofs, are pricing the variable that actually moves the loss. Carriers that rate hail off territory alone are averaging across a risk characteristic that varies enormously within any ZIP code.

Geography still matters, but it has to be resolved more finely than the old territory scheme allowed. Cotality's data concentrates risk sharply: Texas alone carries nearly 8 million properties and $3.1 trillion of exposed reconstruction value, and the Texas Triangle of Dallas-Fort Worth, Houston, Austin, and San Antonio accounts for more than $2.2 trillion of that exposure. A rate that captures this concentration needs territory definitions and class-plan refinements that reflect modeled hail frequency at a far higher resolution than the multi-county territories many filings still use, paired with the property-level roof and construction variables that determine how a given storm converts into a claim.

Deductibles and Policy Structure as Severity Controls

Pricing is only half of the SCS response; policy structure carries the other half, and the two have to be set together because the deductible determines what share of the modeled loss the rate actually has to fund. The industry has moved toward percentage wind and hail deductibles, typically one to five percent of the insured value rather than a flat dollar amount, which scales the retained loss with the size of the home and strips out the high-frequency, low-severity claims that make hail uneconomic to insure at a flat deductible. Cosmetic-damage exclusions, which decline to pay for dents to metal roofing and siding that do not impair function, remove a category of disputed marginal claims that inflate severity without reflecting real damage.

Actual cash value roof schedules, which depreciate the payout on an older roof rather than paying full replacement cost, are the structural counterpart to roof-age rating: they align the claim payment with the pre-loss value of the covering and remove the incentive to treat a hailstorm as a roof-replacement program. An actuary pricing a hail-exposed book has to model these provisions explicitly rather than assume a ground-up loss, because a one percent hail deductible on a $400,000 home retains $4,000 of every event and changes the frequency that reaches the policy. The rate, the deductible, and the coverage form are a single pricing system, and a model run on a ground-up basis will overstate the premium need on a book that has already moved its retained layer.

The Reinsurance Attachment Problem

Even a well-priced primary book has to contend with where its reinsurance now attaches. Through the hard market of 2023 and 2024, reinsurers raised property catastrophe attachment points sharply and pulled back from the aggregate covers that used to absorb a season of accumulated severe convective storm losses. The result is that more SCS loss stays net with the primary carrier, because the events are frequently large enough to hurt but individually too small to pierce a high occurrence attachment, and the aggregate protection that would have caught their accumulation has thinned. Property catastrophe reinsurance softened somewhat at the 2026 renewals, but the structural shift toward higher retentions and away from aggregate SCS cover has largely held.

That changes the primary actuary's job in a concrete way. The SCS load in the rate has to fund the net retained position, not the gross modeled loss, which means the pricing model and the reinsurance structure have to be solved together rather than in separate departments. A carrier that prices to a gross expected loss and then cedes less of it than it used to will be underfunded on its own account, and a carrier that has bought down its retention has paid for protection it must recover in the rate. The reinsurance program is no longer a backstop applied after pricing; for severe convective storm it is one of the inputs to the rate.

Pricing the Peril the Loss Data Already Describes

The through-line is that severe convective storm has graduated to a primary peril faster than the ratemaking around it has, and the carriers that keep pricing it from a short loss triangle will alternate between apparent adequacy in quiet years and rate shock after bad ones, never holding a stable, defensible indication. The path to a stable rate runs through a forward-looking stochastic model rather than the triangle, exposure data resolved to roof age, material, and modeled hail frequency rather than territory averages, deductible and coverage structures modeled as the severity controls they are, and a reinsurance program treated as a pricing input rather than an afterthought. None of these tools is new; hurricane and earthquake pricing has used all of them for years. The shift that 2026 forces is applying the primary-peril toolkit to the peril that is now doing the most damage, before another season writes the lesson into the loss run.