Data sources

Every figure on this site comes from public data, and each page says when it was last updated.

• Live warnings and watches: the National Weather Service API, loaded in your browser and refreshed every minute.
• Radar: NEXRAD base reflectivity tiles from Iowa State University's Iowa Environmental Mesonet, shown in grey so radar never looks like a warning.
• Tornado history: the NOAA Storm Prediction Center severe weather database, 73,458 tornadoes from 1950 to 2025. Paths are straight lines between recorded start and end points. Deaths and injuries are totals for each tornado's whole path.
• This year's tornadoes: SPC preliminary storm reports, labelled preliminary until NOAA confirms them.
• Counties and ZIP codes: US Census Bureau gazetteer files. Address search uses the free Census Geocoder.
• Base map: OpenFreeMap, © OpenMapTiles, data from OpenStreetMap.

Damage figures are not shown yet, because NOAA's damage field changed units over the decades and we want to present it consistently.