It's fun to play in the Sun but too much ultraviolet (UV) radiation can cause serious health effects.
The UV Index helps you plan your outdoor activities, prevent overexposure to the Sun, and take appropriate action, such as wearing a hat, sunglasses, and sunscreen.
The U.S. National Weather Service measures ultraviolet levels on a daily basis, and uses these numbers for various exposure levels. See chart below.
"Time to Burn" and "Actions to Take" apply to people with fair skin that sometimes tans but usually burns. People with lighter skin need to be more cautious. People with darker skin may be able to tolerate more exposure.
You can find out what the UV Index forecast is where you live by visiting this page  and entering your zip code.