«You don’t need sun screen when it’s overcast» – true?

Natalie Hemengül

10/7/2025

Translation: Jessica Johnson-Ferguson

When the sun’s hiding behind a layer of clouds, the idea of applying sun cream is quick to disappear into the shadows. And yet, a large proportion of UV rays continue to reach us.

Honestly, though, do you apply suncream when it’s cloudy out? If your answer is no, you’re not alone. And also understandable. Why protect yourself from the sun you can’t see or even feel? Unfortunately, this is a fallacy, as Joëlle Jufer, prevention expert at the Swiss Cancer League, explained to me: «Cold and cloudy weather can be deceptive when it comes to the actual UV radiation intensity. Even when the sky’s overcast, up to 80 per cent of UV rays penetrate the cloud cover.»

In other words, the temperature says nothing about the UV intensity. «A cool, cloudy day can be just as dangerous as a hot, sunny day,» the expert warns. In addition, light-coloured surfaces such as snow, water, sand or concrete reflect the UV rays and may increase their effect. That’s why you should also wear sunscreen on cloudy days. «The UV index, which is updated daily on Meteo Switzerland, for example, is a good guide. Active sun protection is important for anything over a UV index of 3.»

Why is UV radiation dangerous anyway? «UV rays can damage the genetic material of the cells in our body. To a certain extent, the body can repair this DNA damage. However, individual cells may remain damaged and later turn into cancer cells. What’s more, UV radiation also makes our skin age faster.» Skin melanoma is the fourth most common cancer in Switzerland according to the Federal Statistical Office. The Federal Office of Public Health also mentions that Switzerland has one of the highest rates of skin cancer in the world (page in German).

About Joëlle Jufer

Joëlle Jufer is a qualified nurse and health promoter. As a prevention expert at the Swiss Cancer League, her focus is on sun protection. She’s committed to raising awareness about skin cancer and motivating people to take a healthy approach to UV rays. She feels that prevention work is an important tool for reducing non-communicable diseases and improving people’s quality of life in the long term.

This article is part of a miniseries on sun protection in collaboration with the Swiss Cancer League. Find all published articles here:*

Natalie Hemengül

Senior Editor

Natalie.Hemenguel@digitecgalaxus.ch

As a massive Disney fan, I see the world through rose-tinted glasses. I worship series from the 90s and consider mermaids a religion. When I’m not dancing in glitter rain, I’m either hanging out at pyjama parties or sitting at my make-up table. P.S. I love you, bacon, garlic and onions. more

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