UV Index Explained: What It Means for Your Skin and Health

Weather apps show plenty of numbers: temperature, humidity, wind speed, rain chances. But there is one measurement many people still ignore completely: the UV Index.

You have probably seen it sitting in your daily forecast, but what does it actually mean? Those numbers measure the expected strength of ultraviolet radiation from the sun. The higher the number, the faster unprotected skin and eyes can be damaged. The UV Index is especially useful because you cannot feel UV radiation the way you feel heat. A cool, breezy day can still come with a high UV risk.

UV radiation changes throughout the day, across seasons, and from place to place. It can affect how quickly skin burns, how much cumulative sun damage builds up, and how much protection you need before heading outside.

How the UV Index Works