The UV Index provides a forecast of the expected risk of overexposure to UV radiation from the sun. The National Weather Service calculates the UV Index forecast for most ZIP codes across the U.S., and EPA publishes this information. The UV Index is accompanied by recommendations for sun protection and is a useful tool for planning sun-safe outdoor activities.

 

Ozone depletion, as well as seasonal and weather variations, cause different amounts of UV radiation to reach the Earth at any given time. Taking these factors into account, the UV Index predicts the level of solar UV radiation and  indicates the risk of overexposure on a scale from 0 (low) to 11 or more (extremely high). A special UV Alert may be issued for a particular area, if the UV Index is forecasted to be higher than normal.

 

The forecast map shows contour lines of predicted UV Index values during the solar noon hour. The map is created daily from National Weather Service forecast data. Click the buttons for Day 2, Day 3, or Day 4 to see the UV Index forecast for following days. You may notice a brief delay as each map loads. (To find the time of solar noon at your location, use the sunrise-sunset-solar noon calculator at the NOAA website.)