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Do clouds block UV rays? All about UV exposure on cloudy or rainy days

On sweltering summer days, you can practically feel the sun’s ultraviolet rays burning you — or you would if you didn’t have chic sun protection keeping you safe. In contrast, cloudy weather usually feels cool on the skin. With that kind of temperature difference, you may think it’s safe to skip sunscreen. The truth is, you can actually get MORE UV radiation on overcast days, so it’s a smart idea to wear sunscreen no matter what the forecast calls for. 

Do clouds block UV rays?

Clouds can reduce the UV rays your skin has to contend with, but they don’t actually protect you. If you want to keep your beautiful skin healthy and hydrated for the long haul, you need sunscreen on cloudy days. Put simply, if you’re going outside, wear sunscreen.

An interesting way to observe this phenomenon is by looking at the UV Index on your phone’s weather app. On cloudy days, you may sometimes find that the UV Index is higher than on a sunny day. Sometimes, cloudy days have UV indexes that are “extreme” while the index of a regular sunny day in your area can be “moderate” or “high”.

Do UV rays hurt even if you don’t get sunburned?

On cloudy days, UV rays can still be absorbed into your skin; our skin is still getting hit with damage.

We’re not going to bore you with scientific jargon, but you should know that there are two types of ultraviolet radiation you should avoid: UVA and UVB.

UVB rays are the pointy-mustached villains that cause sunburns—obviously evil. UVA rays are trickier, like con artists running the long game. They look all innocent-eyed but secretly raise your risk of skin cancer and damage deeper layers of skin.

Do clouds protect you at all?

OK, so clouds don’t completely protect you, but can they provide a moderate level of protection? Yes, but it's limited. Clouds are not a valid form of sun protection that you can count on. In fact, a whopping 90% or more of UV radiation makes it through fluffy white clouds. It’s important to cover up, even on overcast days.

Do clouds block UV rays in winter?

Another common misconception is that you only need to protect your skin against UV rays during warmer months as if the sun stops putting out energy for part of the year. Here’s the truth:

  • Exposed skin can get sunburned any time of year.
  • Overcast days don’t protect your skin against UV rays.
  • The temperature has nothing to do with the strength of the sun’s rays.
  • Snow and ice reflect UV rays onto your face, actually increasing exposure and risk of sunburn.

Of course, if you’re walking around bundled up from head to toe, you don’t have much to worry about because your skin is covered up — that’s the reason we have fewer problems with sunburns in the winter, not because the UV rays are less intense.

Do clouds block UV rays at work?

If you’re inside on a cloudy day, you do get an additional layer of protection from UVB rays. This is good, but there’s always room for improvement. Unless your boss has invested in next-gen windows with UV coatings for the office, you’re still getting exposed to plenty of UVA rays. Be sure to keep sunscreen handy for reapplications if you’re sitting directly by a window.

Do clouds block UV rays? Better options

Now, for some good news: Protecting your skin doesn’t need to be complicated. Sun-protective clothing with long sleeves does a fantastic job of blocking UV rays, and today’s modern formulations make applying sunscreen as easy as slathering on a smooth hand cream.

At Clair Obscur, we’re dedicated to providing expert-sourced answers to all your sun care questions. Learn more about how to stay sun safe every day, all year round.