When you're trying to figure out how much sun protection you need, your weather app isn't the only tool that can help. Created by the National Weather Service and Environmental Protection Agency (EPA) in 1994, the UV Index Scale measures the intensity of ultraviolet (UV) radiation levels and estimates your risk of overexposure to the sun's rays.

Infographic showing the UV index and sun safety facts and tips

The scale is broken into three levels: low, moderate, and high to extreme. Each level of the UV Index Scale comes with its own helpful tips for planning your sun protection.

0-2: Low

This is when the UV radiation level is at its lowest. The EPA says that it's safe to go outside with minimal sun protection. That said, wearing sunscreen daily regardless of the number on the scale is always a good idea. By protecting your skin from the sun each day, you not only prevent sunburns and skin cancer but discoloration, wrinkles, and other signs of premature aging, as well.

3-7: Moderate

"Moderate" doesn't sound too bad, but according to the EPA, it's important to seek shade when the index is at this level. This is especially important from late morning through mid-afternoon while the sun is at its highest. Protect your skin from the sun's harmful UV rays by wearing sun-protective clothing, a wide-brimmed hat, and sunglasses.

On moderate days, it's recommended to wear a broad-spectrum sunscreen of SPF 30 at the minimum. According to the Skin Cancer Foundation, the number following SPF measures how long the sun's UV rays are going to take to redden your skin compared to going without any sun protection. For example, a sunscreen with SPF 30 means that it would take 30 times longer for you to get burned than if you used no sunscreen.

8+: Very High to Extreme

This is when you'll need extra protection. Be very careful when you're outside, and apply the "shadow rule." This rule says that if your shadow is taller than you, your UV exposure is low. If your shadow is shorter than you, then the sun is higher and brighter, and you're exposed to higher levels of UV radiation.

During high to extreme days, you should seek shade immediately and wear sunglasses to protect your eyes. You'll want to not only use a broad-spectrum sunscreen but reapply carefully every two hours. While the EPA says you don't have to seek out a higher-SPF sunscreen, many experts recommend at least SPF 30 to be safe.

The UV Index Scale can be your guide to sun protection on the hottest outdoor adventures. It's just another way to be smart when dealing with UV rays and enjoying your time in the sun.

Author

  • Audrey Noble is a New York City-based reporter specializing in features, celebrity profiles, and beauty topics. Her work has appeared in Vogue, Harper's BAZAAR, Allure, Vanity Fair, Refinery29, and more. She is a University of Southern California alumna with bachelor's degrees in print journalism and creative writing.