What Hail Radar Can (and Can't) Prove

What weather radar can establish

Weather radar — the NEXRAD network and the NOAA MRMS system built on top of it — is very good at answering a specific, bounded question: was there hail in this area, on this date, and roughly how large? For a given address, the radar record can establish a few things with real confidence.

• That a hail-producing storm passed over or near a location, and the date and approximate time it did.
• An estimate of the largest hail the storm was capable of producing in that area (MRMS calls this MESH — Maximum Estimated Size of Hail).
• The spatial footprint of the storm — which neighborhoods and streets fell inside the hail area and which did not.
• How the storm fits into an address's longer history — whether this was a rare event or one of many.

This is genuinely useful. It is the context that tells a homeowner whether it's even worth getting a roof looked at, and it gives an adjuster or inspector a documented, government-sourced date of loss to work from.

What weather radar cannot establish

Radar sees the storm, not your roof. That distinction is the whole thing, and most tools in this space blur it. Here is what the radar record genuinely cannot tell you:

• Whether your specific roof was struck. Radar estimates the largest hail the storm could produce over an area; hail size and coverage vary block to block and even between two houses on the same street.
• Whether your roof was damaged. Impact does not always equal damage — roof age, material, slope, and angle all matter. That is an inspection question, not a radar question.
• The exact hail size at one point. A radar estimate is a class, not a measurement — MESH is tuned so that roughly 75% of measured hail comes in at or below it — and a physically measured hailstone on the ground remains the gold standard.
• What caused a particular mark on your roof. Radar cannot distinguish a hail bruise from wind scuffing, foot traffic, or age-related wear.

Why the distinction matters

This is not hair-splitting. It matters for three practical reasons.

• Trust: a homeowner who is told 'you have damage' and then has an inspector find none learns not to trust the tool. 'Your address was exposed to 2-inch hail on this date — worth an inspection' is both more honest and more durable.
• Insurance: a claim rests on the actual condition of your roof, documented by an inspection, with the storm's date of loss as supporting context. Overstating the radar record doesn't strengthen a claim — an accurate, source-cited exposure record does.
• Credibility under scrutiny: a proprietary 'damage score' nobody outside the vendor can reproduce asks you to take its word for it — there is nothing underneath to check. A record that points to the raw NOAA and NEXRAD event IDs behind every data point is one anyone — a homeowner, an adjuster, an engineer — can verify against the public NOAA archives.

How HailScore uses radar honestly

HailScore is built entirely around this line. It scores hail exposure — how much hail an address has been in the path of, drawn from 41.2M+ NOAA, NEXRAD, MRMS, SPC, and CoCoRaHS records — and it says so plainly. It never claims to confirm damage.

• Storm pages name their NOAA source, and events in the paid storm-history report carry a NOAA or NEXRAD source ID wherever the source publishes one.
• Radar-estimated sizes are always labeled as estimates and read as a size class, not a measurement.
• The recommended next step is always a physical inspection — the only thing that actually confirms damage.

Frequently asked questions