September 23, 2014


UV Index

The UV Index indicates the strength of solar ultraviolet radiation on a scale of 1 to 11+. A UV index of 1 is low while 11+ is considered extremely high. The ozone layer plays an important role in determining the UV index. Responsible for shielding the planet from harmful UV radiation, the ozone layer has been depleted to the point that it can be very unsafe for human beings to spend ample time in the sun. This depletion of the ozone, as well as variations in the seasons and weather, causes different amounts of UV radiation to reach the Earth at any given time. As a result, a daily UV Index was developed to protect people from potentially harmful UV radiation. The National Weather Service calculates the UV Index for the next day in each area of the United States. The forecast is published in mid-afternoon in the Eastern Time zone and, if the level of UV radiation is expected to be especially high, the forecast will include a UV Alert. The forecast for the following day’s UV Index is published on the Environmental Protection Agency Web site ( every day by mid-afternoon. Those especially concerned about exposure to UV radiation can even sign up for e-mail notification alerts.