Before you head outside, you may check the weather forecast to determine how you should dress for the day and, perhaps, whether you should apply sunscreen. What you might not check as regularly is the ultraviolet (UV) index scale.

But, what is the UV index exactly? Keep reading to learn why this scale is important and how to check the UV index in your area.

What Is the UV Index?

The UV index scale was developed in 1994 by the National Weather Service and Environmental Protection Agency (EPA). According to the EPA, the scale measures the intensity of UV radiation levels and provides a daily forecast of the risk of overexposure to the sun's rays. Learning about the UV index, especially in your area, can help you make informed choices to protect yourself before you go outside.

The UV index predicts this risk on a scale from 1 to 11+. The levels of the UV index represent the corresponding exposure categories:

  • 1-2: Low

  • 3-5: Moderate

  • 6-7: High

  • 8-10: Very High

  • 11+: Extreme

The EPA has sun protection recommendations for each of the five exposure categories. Even at the lowest exposure levels, sunscreen application is encouraged to prevent sunburns, sun damage, and the harmful effects of overexposure to UV radiation.

How the UV Index Is Determined

There are many factors that affect the UV index, including cloud cover, altitude, location, seasons, day of the week, and more.

The UV index levels change throughout the day, but in the UV index forecast, only a single value will be presented for the whole day—typically the maximum value. For example, the UV index might be 1 at 7 a.m. but rise to 8 at noon, when the sun is strongest. The UV index would not be the average of these numbers but rather the highest level to prepare people for the highest risk. So, in this example, the UV index that day would be an 8.

How to Check the UV Index

Like checking the weather to determine how to dress, checking the UV index helps you make informed, healthy choices regarding sun protection measures. When you're wondering if you should apply sunscreen before going outside, taking the UV index into account can equip you with the information needed to make that decision. The findings may convince you to apply a broad-spectrum sunscreen.

In most places in the U.S., the UV index ranges from moderate to very high throughout most of the year, so applying sunscreen on a daily basis is a good habit to form. To find your local UV index, simply check the weather. Weather forecasts usually have a report on the UV index for the day. The EPA also recommends a mobile app specifically for the UV index.

Being aware of the UV index helps you to stay informed about the potential risk of UV overexposure, but don't skip wearing sunscreen on days with low exposure levels. In the end, your skin will thank you.

Author

  • Lacey is a Southern California-based freelance writer who combines her passions—fitness, health, and a vegan lifestyle—with her work to help readers feel and be their best. Her work has been featured in Healthline, Livestrong, Verywell Fit, Eat This Not That, KinderBeauty, and more.