How High Does the UV Index Go

By: Margaux Reese
February 21, 2023

No matter when you go outside, you should make sure your skin is protected. That’s why you should take a look at the UV index.

But what is the UV index, and what does it tell you? The UV index tells you how strong the sun’s rays are on a given day.

By understanding the UV index chart, you'll have a better idea of how intense the sun’s rays are that day and be able to protect yourself accordingly.

In this guide, we’ll answer your most pressing questions like “how high does the UV index go?” and give you tips for how you can use it to plan to keep your skin protected. Keep reading or use the links below to take the first step toward better sun care.

What Is the UV Index?

The weather UV index gives you an idea of how strong the sun’s ultraviolet radiation is that day. Typically, the UV index chart will also show a UV alert when the level of UV radiation that day is expected to be unusually high.

How high does the UV index go? The UV index chart goes from 1 to 11+, with 11+ being the highest.

Blue and gray graphic with text that reads, “UV Index: A forecasting tool that's used to show how strong the UV rays are that day and the risk associated with sun exposure.”

It’s important to note that the UV index isn’t the same everywhere. Just as weather patterns vary from place to place, the UV index in one location could be different from the UV index somewhere else.

The greater the UV radiation on the index that day, the more important it is for you to take steps to protect yourself. If you expose yourself to significant amounts of UV radiation for long amounts of time, you increase your chances of developing chronic skin conditions down the road.

How Does the UV Index Work?

So, what is the highest UV index? The UV index is broken up into several categories:

  • Low: A UV index of 2 or less is considered low.
  • Moderate: A moderate UV index is 3 to 5.
  • High: A high UV index is 6 or 7.
  • Very High: If the UV index is 8 to 10, it’s considered very high.
  • Extreme: Finally, extreme UV radiation is 11+

By checking the UV index before you go outside, you'll have a better understanding of whether you need to take extra measures to protect your skin.

UV index with numbers going horizontally from 1 to 11+ with images of different versions of the sun above them. On the left end of the spectrum, it reads “minimal danger” and on the right end of the spectrum, it reads “very high risk”.

You should also know that there are several factors that impact the UV index. What changes the UV index on a given day? A few factors include:

  • Cloud Cover: If you see a lot of clouds in the sky, they block a lot of the UV rays from reaching the surface of the earth. Therefore, the UV index on a cloudy day is going to be slightly lower than it is on a sunny day.
  • Ozone Thickness: Have you heard about a hole in the ozone layer? The ozone layer is thicker in some parts of the world than in others. If the ozone layer is thicker, you have more protection, and the UV index might be lower.
  • The Intensity of the Surface: Does the surface of the ground around you look bright and shiny? If snow, sand, and water reflect light from the surface, the UV index might be higher.
  • Air Pollution: Air pollution is bad for your health. It can lead to a variety of chronic medical issues. On the other hand, air pollution can also lead to smog, which blocks some of the UV rays from reaching the surface. If the air is polluted, the UV index might be lower.

Any and all of these factors can impact the UV index on a given day, so be sure to check it before going outside.

Types of UV Rays

There are several types of UV rays. They are usually broken up into ultraviolet A, ultraviolet B, and ultraviolet C rays. These terms are usually shortened to UVA, UVB, and UVC.

According to the CDC, the ultraviolet rays that come from the sun are broken up based on their wavelengths as follows:

  • UVA: 315 to 399 nm
  • UVB: 280 to 314 nm
  • UVC: 100 to 279 nm

These wavelengths are important because they dictate which rays can reach the surface of the earth. For example, UVA rays are usually not absorbed by the ozone layer. Therefore, the vast majority of ultraviolet radiation that reaches the surface of the earth is UVA.

Because UVB rays have slightly different wavelengths, not all of them are absorbed by the ozone layer. Even though most of them are, there are some UVB rays that still reach the surface of the earth. That's why you need to wear sunscreen that protects against both UVA and UVB rays.

Do you need to wear sunscreen that protects against UVC radiation?

When it comes to UVC rays specifically, it’s usually not necessary. Because UVC rays have a different wavelength than UVA and UVB rays, they are completely absorbed by the ozone layer and the other components of the atmosphere. That's why they don't reach the surface of the earth, so they should not strike your skin, either.

Young white woman with a tan wearing a pink bathing suit and squeezing sunscreen into her hand.

Do you need to wear sunscreen that protects against UVA and UVB rays?

Yes, you need to protect against UVA and UVB radiation because both of them can have an impact on your overall health. In general, UVA rays are able to penetrate deeper into the skin. However, both UVA rays and UVB rays are dangerous and can cause health issues. While UVA rays are typically responsible for skin damage like sun spots or even skin cancer, UVB rays cause burning.

When choosing a sunscreen, you’ll want a broad-spectrum formula for protection from both types of rays.

How the UV Index Impacts You

The UV index dictates how intense the sun exposure will be if you go outside. For example, you might be curious about the UV index to tan or the UV index burn time. In general, the higher the UV index score is, the more protection you need when you go outside.

For example, if the UV is high, meaning a score of 6 or higher, you could suffer a burn in just a few minutes. You will need to take extra protective measures if you go outside when the UV index is high, or you can face serious risks.

On the other hand, if the UV index is low, you might not need to take as many protective measures when you go outside. Of course, it's always important for you to protect yourself with sunscreen and maybe even sunglasses and a hat.

Why Sun Protection Is Important

Sun protection should be a top priority any time you go outside. Yes, even on overcast days.

If you expose yourself to the sun for too long, it can lead to a variety of short-term and long-term health issues. In the short term, harmful UVA rays can lead to a sunburn. Some of the signs that you have a sunburn include:

  • Redness
  • Swelling
  • Fatigue
  • Hypersensitivity
  • Tenseness

If you stay out in the sun for too long, you could get sun poisoning. This can lead to extreme sunburns with blisters while also causing you to feel confused and delirious. It could even end in a medical emergency, so you need to protect yourself accordingly.

Additionally, constant exposure to high levels of UV radiation can lead to long-term health impacts. For example, repeated, chronic sunburns could increase your chances of developing skin cancer, like melanoma, which can spread to other parts of the body quickly.

Long-term, repeated exposure to high amounts of UV radiation can also cause your skin to age prematurely. Over time, your skin could begin to look like leather, and it might have more sunspots, fine lines, and wrinkles than it otherwise would.

If you want to prevent these painful and often dangerous side effects, you should always wear protection when you go outside.

Shield with a check mark and text that reads, “3 Ways to Protect Yourself from UV Rays: 1. Use broad-spectrum sunscreen. 2. Wear protective clothes. 3. Avoid the sun when it’s strongest.”

How to Protect Yourself from Harmful UV Rays

Even though UV rays can be dangerous, there are plenty of ways you can protect yourself with minimal effort. Some of the best ways for you to protect yourself against the sun's UV rays include:

  • Avoid the sun during peak hours: You should stay out of the sun when the sun’s rays are at their strongest. Generally, this means avoiding exposure during the early afternoon.
  • Wear a hat and protective clothing: You also need to wear a hat when you go outside. Wearing a hat can help you keep the sun’s rays off your face and neck. Even though it might be a bit hot outside, wearing full-coverage clothing can guard your skin against UV radiation.
  • Wear sunglasses: Don't forget about protecting your eyes as well. Chronic exposure to high UV radiation can increase your chances of developing cataracts. By wearing sunglasses, you can keep UV radiation out of your eyes.
  • Wear the right sunscreen: Finally, you need to wear broad-spectrum sunscreen that protects against both UVA and UVB radiation. Look for a mineral sunscreen that reflects UV rays away from the skin.

By taking these protective measures, you can enjoy your time outdoors without putting yourself in harm's way. Just make sure to always reapply!

Understanding the UV Index Can Help You Stay Healthy

Before you go outside, always take a look at the UV index to understand how intense the sun's radiation is that day. If the UV index is 6 or higher, you should take extra precautions to protect your skin against the sun.

Most importantly, always make sure to wear sunscreen to reduce your chances of developing both short-term and long-term health issues. Looking for a sunscreen you can trust to provide high-quality protection? Try Colorescience mineral sunscreen. Our broad-spectrum sunscreens are available in a variety of application methods, so it’s easy to protect your skin on the go.