When ultraviolet radiation levels get high, EPA's UV Index app warns consumers when they've had enough sun exposure. Powered by the National Weather Service, the app delivers a daily and hourly forecast of the expected intensity of UV radiation nationwide. Hourly forecasts are color-coded (green, orange, red, and yellow) to represent low, moderate, and high UV intensity. The app lists the risks of overexposure to the sun and reminds users to take precautions, such as wearing a hat, sunglasses, and sunscreen. UV Index is available for the Apple, Android, and BlackBerry platforms.