How the hail history pages are built
Every county and state page under hail history comes from one public file and the same counting rules. They are written down once here so the pages themselves can stick to the numbers.
Where the numbers come from
The source is the NOAA Storm Events Database, which stores one row per hail report: date, county, size in inches, a place name and sometimes a coordinate and a text note. We use county-level rows from January 2014 through June 2026. NOAA's file stopped at June when we loaded it on 2026-10-06, so every 2026 figure is a half year and is marked that way. Rows hold reports from spotters, trained observers, emergency managers and the public. One storm can produce dozens of rows, and a county with more observers produces more rows, so a count is a measure of reporting as much as of weather.
What counts as a hail day
A day counts toward "days 1 in+" when at least one report of 1 inch or larger was filed in the county that day. The National Weather Service calls hail of 1 inch or larger severe. "Days 1.75 in+" applies the same rule at golf-ball size. A counted day says hail was reported somewhere in the county; it does not say your roof was hit. An inspection is the only way to know.
The size scale
Stone sizes are described by common objects, the way the National Weather Service does it. Spotters estimate by comparison, so sizes carry error, and a report of "baseball" can be a stone from 2.5 to 3 inches.
| Inches | Object |
|---|---|
| 0.75 | penny |
| 1 | quarter |
| 1.25 | half dollar |
| 1.5 | ping-pong ball |
| 1.75 | golf ball |
| 2 | hen egg |
| 2.5 | tennis ball |
| 2.75 | baseball |
| 3 | teacup |
| 4 | grapefruit |
| 4.5 | softball |
Roofing materials respond differently across that range. Asphalt shingles start to lose granules and crack as stones approach golf-ball size, while metal and flat membranes are dented or punctured by the larger stones. Damage also depends on wind, roof age and the material under the surface, so size alone does not settle a claim.
Reading the map
Each dot is one report of 1 inch or larger that came with a coordinate. Color marks the size band: amber from 1 inch, orange from 1.75 inches, red from 2.75 inches. A dot sits where the observer placed the report, not on a measured storm path, and reports without a coordinate are counted in the tables but not drawn. When a county has more located reports than we can draw cleanly, the map shows the largest ones. County outlines come from the Census Bureau cartographic boundary files.
The roof calculator
The year box adds up the year-by-year table from the year you enter through 2026. Roofs installed before 2014 have also been through earlier hail that this record does not hold, and a roof newer than the record falls outside it.
Rankings and density
Reports per 1,000 square miles divides a county's reports by its land and water area, which lets a small county be compared with a large one. State ranks compare counties with 30 or more reports. State totals add up counties that hold 30 or more reports or a city we cover, so a rural county with a handful of reports sits outside the totals.
Tornadoes and wind
Tornado rows list NOAA's rating, path length and width. Wind gusts reported in knots are converted to miles per hour. Both are measured or estimated after the event.
Housing and building permits
Home age comes from the American Community Survey, 2019 to 2023 five-year estimates, and is the year a structure was built, not the year its roof was last replaced. Permit counts come from the Census Bureau Building Permits Survey for 2014 to 2025 and cover new housing units, so they track construction rather than reroofing. Permit values are the construction cost stated on the permit, land excluded.
Photo credits
The example photos on the county and state pages are public-domain U.S. government works, taken from Wikimedia Commons. They show typical hail of that size and are not pictures of the county they appear on.
- Street covered in hail: NOAA Photo Library, OAR/ERL/National Severe Storms Laboratory (Commons).
- Baseball-size hail on burlap: OAR/ERL/Wave Propagation Laboratory, NOAA Photo Library (Commons).
- Golf-ball-size hail cut open, near Roosevelt, Oklahoma, April 9, 1978: NOAA Photo Library, National Severe Storms Laboratory (Commons).
- Windshield broken by a baseball-size stone, Moore, Oklahoma, May 25, 2010: Win Henderson, FEMA (Commons).
Limits
These pages describe what was reported, not what will happen, and they are not legal or insurance advice. Check the deadline rules for your state on the claim deadlines pages.