Data

Source of Forecast Data

UVIndexToday.app uses ultraviolet index forecast data published by NOAA, the National Oceanic and Atmospheric Administration. NOAA is a United States government agency that publishes operational weather and environmental datasets, including UV guidance.

The UV values shown on this site are derived from NOAA forecast data and then matched to states, counties, places, and other supported geographic areas on the site. The numbers are based on forecast model output rather than a sensor at each destination page.

NOAA releases new forecast data once a day. Values on UVIndexToday.app may change when that daily forecast is updated upstream.

Method of Data Presentation

UV forecast grids are processed into daily peak UV Index values and hourly patterns for the locations shown here. Those values are also converted into risk categories based on standard EPA UV Index guidance for easier reading.

NOAA is the source of the forecast, but UVIndexToday.app is an independent presentation of that data for browsing and comparison. This site is not an official NOAA property, product, or publication.

Forecast Limitations

Forecast UV values represent expected conditions over an area and time window. Actual UV exposure at your location can still vary because of clouds, smoke, elevation, reflective surfaces, shade, and other local factors.