Hail Size and Roof Damage: What the Weather Service Logged Near You

The thresholds the Weather Service uses

A thunderstorm is severe, and gets a warning, when it produces hail of 1.00 inch (quarter-sized) or larger, or winds of 58 mph or more. The threshold was raised from 0.75 inch (penny-sized) on January 5, 2010, which is why hail counts before then are not comparable. Since 2021 warnings also carry a damage-threat tag: considerable at 1.75 inch (golf-ball) hail or 70 mph wind, and destructive at 2.75 inch (baseball) hail or 80 mph wind.

Sizes are the Weather Service's reporting conventions. The damage column is what roofers and adjusters commonly find at each size on asphalt shingles in reasonable condition; a fifteen-year-old roof fails sooner and a Class 4 impact-rated shingle later. It is a guide to expectation, not an inspection.

What Tennessee's record looks like

NOAA's Storm Events Database holds 1,610 hail reports for Tennessee from January 2016 to September 2026. 1,271 of them, 79 percent, were an inch or larger, because a report under an inch is rarely worth a spotter's call. 82 were two inches or larger.

The counties with the most reports are Williamson (99, with 17 at two inches or more), Davidson (69), Shelby (66), Madison (52), Sumner (43), Knox (42), Wilson (40) and Robertson (39). Williamson's count is not a quirk of geography alone: it is one of the most densely spotted counties in the state, and a county with more trained spotters logs more hail. What the numbers can say is that the Franklin, Brentwood and Nolensville corridor has seen more large-hail reports than anywhere else in Tennessee in the last decade, including three-inch hail at Leipers Fork in May 2024.

How to use the town pages

1. Look at the largest size, not the count. A town with forty penny reports and one golf-ball report has had one roof-damaging day.
2. Read the notable reports. Each town page lists the five biggest events with the spotter's own narrative and the date. That date is what you give your insurer; hail claims have deadlines measured from the storm, usually one or two years depending on the policy.
3. Match the date to your roof's age. A roof installed after the last big event has not been hit. A roof older than it may have damage nobody has looked for.
4. Do not let the storm roofer read the chart for you. Two-inch hail on the county page does not mean two-inch hail on your street. The inspection decides, and the claim process starts with your insurer, not a contract.

Where the reports come from

A Storm Events entry is a report the Weather Service accepted from a trained spotter, a cooperative observer, an emergency manager, law enforcement, the public or its own staff, with the size, time and location as reported. Sizes are estimates against common objects, rounded to the nearest convention, and the location is the point the report came from, which is why this site counts events within twelve miles of a town rather than pretending to street-level precision.