About the data

NOAA Storm Events Database. Final records of hail and tornadoes that the National Weather Service collected and NOAA's National Centers for Environmental Information publish each month, about three months after the event. We use every hail, tornado and thunderstorm wind record since 2006: date and time, hail size in inches, wind gust in miles per hour (NOAA stores knots; measured or estimated), the place and its coordinates, and the NWS description of the largest storms. Public domain.

NWS Local Storm Reports. For the months after the latest NOAA release we show the preliminary reports that spotters, the public, emergency managers and the media send to the National Weather Service, collected by the Iowa Environmental Mesonet. They are checked hourly and replaced by the final NOAA records when those come out. Preliminary reports can contain errors.

What a report means. A report says hail of that size was seen at that place and time. Hail falls in narrow swaths: a report 3 miles away does not prove hail fell at a particular house, and hail can fall where nobody reported it. Distances on city pages are measured from the center of the city (GeoNames coordinates, CC BY 4.0); dates are local time at the report's location.

Not advice. This site does not assess damage or insurance claims. We are not affiliated with NOAA, the National Weather Service or the Iowa Environmental Mesonet.