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UV Index
UV Index |
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| UV Index forecast |
UV Index scale |
How UV Index is calculated |
UV Alert |
Health effects of overexposure |
UV Index resources |
Forecast map | Lookup your UV Index | Related links
The ozone layer shields the Earth from harmful ultraviolet (UV) radiation. Ozone depletion, as well as seasonal and weather variations, cause different amounts of UV radiation to reach the Earth at any given time. The UV Index, developed by the National Weather Service and EPA, indicates the strength of solar UV radiation on a scale from 1 (low) to 11+ (extremely high).
Every day the National Weather Service calculates the predicted UV Index for the next day in each area of the U.S. This UV Index forecast is published in mid-afternoon (Eastern time zone) at the EPA Web site. If the level of solar UV radiation is predicted to be unusually high, and consequently the risk of overexposure is greater than normal, the forecast includes a UV Alert. (You can sign up below to receive e-mail notification of UV Alerts for your community.)
UV Index forecast map
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 Web site.)
Lookup your UV Index
You can use the UV Index to take appropriate sun-protective behaviors and avoid overexposure to UV radiation. Enter ZIP Code or city name and state below to get the UV Index forecast for your community or for a place you are visiting.
Tip: If your ZIP Code is not found, try searching for your city and state. Some ZIP Codes may not be in our database.
You can also look up UV Index using the following resources.
- UV Alert map - Areas in the U.S. where predicted UV intensity will be well above normal, and you will need to be especially careful to avoid over-exposure. (National Weather Service)
- Cities forecast map - Forecast UV Index values for 58 U.S. cities, shown on a map.
- Cities forecast bulletin - A plain text listing of forecast UV Index values for 58 U.S. cities. (National Weather Service)
More ways to get UV Index
Smartphone
Related information
To report UV measurements for your school, please see the SunWise data entry page.
The following UV Index archives and other information are available from National Weather Service:
- Past city forecast bulletins
- Graphs of yearly values for each city
- Monthly averages of the UV Index in the U.S.
- Information about UV radiation and how it varies
- General UV Index information