Hail

Hail

A severe thunderstorm drops hailstones large enough to break roofs, cladding, solar panels and crops. The larger the stone, the larger the damage. Hail prices both Property damage (% of asset value) and Business interruption (% of annual revenue), the latter for component repair and lost solar generation.

What the map shows

• Today: the global size-resolved hail hazard: how often hail of 25 mm or more falls each year, at the scale of a ~1-2 km² storm cell (sheet). This is the legible picture of the hazard; the engine reads companion bands of the same dataset at building scale.
• Projected: none. The layer is a historical climatology with no forward horizon, so the map and the loss do not move with the scenario.

How the loss is computed

The engine reads, at the site's point, the yearly rate of hail of 25, 40 and 60 mm at the scale of a 100 m² building footprint. From these it fits how often each hailstone size falls, and integrates the Schmid (2024) size-to-loss curve over that distribution into an annual loss. Where those bands are missing, for example on some coastal cells, it falls back on the NASA hail density through a calibrated bridge. Business interruption uses a hail-specific downtime, not the shared structural relation. Hail is tagged Built. See Damage functions: Hail and Climate risks.

Sources

• Prein & Holland (2018), global estimates of damaging hail hazard. PANGAEA, doi:10.1594/PANGAEA.893160. CC BY 3.0.
• GridRad-Severe v4.2 contiguous-US radar hail sizes (Murphy & Homeyer), Zenodo 13887225. CC BY 4.0.
• MeteoSwiss Swiss Hail Climatology (CHHC), used for the cell-to-footprint size law. CC BY 4.0. Source: MeteoSwiss.
• Fallback density: NASA Passive Microwave Hail Climatology (PMHC), Bang & Cecil (2019), TRMM and GPM combined, 2° resolution. Licence not confirmed.
• Damage curve: Schmid (2024) cubic size-to-loss.

Limits

• The map grades a storm-cell frequency while the hail row reports a hailstone diameter, so hail carries no exposure grade.
• The crop and hail-robust vulnerability classes are Darwin reconstructions; the building curve is Schmid's published fit.
• The storm-cell bands overstate loss under the cubic curve, which is why the engine reads the building-footprint bands instead of the band the map shows.