The UV index and sunburn risk

  • The sun can be strong enough to cause sunburn from mid-March to mid-October in the UK. 
  • Your risk of sunburn depends on how sun-sensitive your skin is and how strong the sun’s UV rays are.  
  • The UV index tells us how strong the sun’s UV rays are. If it is 3 or above, you need to think about protecting your skin.

Sunburn doesn’t just happen abroad or on summer holidays. The sun is often strong enough in the UK to damage your skin, even if it’s cold or cloudy.


Do I need to protect my skin?

Up to 9 in 10 cases of melanoma skin cancer could be prevented by enjoying the sun safely. So, whether you’re working outside, doing the gardening or sitting in the park, it’s important to be sun smart. When the sun is strong, think about protecting your skin by:

  • Spending time in the shade - take a break under an umbrella, tree, or head inside.
  • Covering upwear loose clothing with a wide brimmed hat and UV protection sunglasses.
  • Using Sunscreen - on bits that you can’t cover with clothes or shade. Use plenty with at least SPF15 and 4 or 5 stars, and reapply regularly.

Find out more about how to enjoy the sun safely


The UV index 

The UV index tells us how strong the sun’s UV rays are and when we might be at risk of burning. The higher the value, the greater the risk of sunburn and the less time it takes to damage your skin.

When the UV Index is 3 or more, the sun is strong enough to cause damage for some skin types so take care and protect your skin, especially if you burn easily.


UV ratings explained

UV 1-2 

Low exposure. No sun protection needed. 

UV 3-5

Moderate exposure. Think about sun protection, especially between 11am-3pm.

UV 6-7 

High exposure. Skin protection needed for most skin tones.

UV 8-9+ 

Very high exposure. Skin protection needed for all skin tones. 

Check the UV index forcast for different parts of the UK on the Met Office website.


When is the sun the strongest - the shadow rule

Another handy tip to help you work out when the sun is strong is the ‘shadow rule’. It’s simple and it works anywhere in the world. It’s also a fun way to talk to children about enjoying the sun safely.

Look at your shadow and if it is shorter than your height this means that the sun’s UV rays are strong. So that’s when you’re more likely to burn and need to take care and protect your skin, especially if you get sunburnt easily.


Who’s at risk of sunburn?

Sunburn, just once every two years can triple your risk of melanoma skin cancer. Anyone can get sunburnt or develop skin cancer, but some people are at a higher risk and need to take more care in the sun.

You should take more care in the sun if you have one or more of the following:

  • skin that burns easily
  • light or fair coloured skin, hair, or light coloured eyes
  • lots of moles or freckles
  • a history of sunburn
  • a personal or family history of skin cancer

You’re the best person to know how your skin reacts to the sun. The more easily you get sunburnt, the more careful you need to be. Remember, you don’t need to peel – if your skin’s gone red, pink, itchy or tender in the sun, that’s sunburn.


Do people with dark skin get sunburnt?

People with naturally dark or brown skin burn less easily and have a lower risk of skin cancer. But people with darker skin can still burn – it might feel itchy or tender rather than changing colour. And people of all skin tones can get skin cancer.

We all need some sun to help produce vitamin D. But people with darker skin need to spend longer in the sun to produce enough of it, so may be at a higher risk of vitamin D deficiency. Talk to your GP about supplements if you are worried about your vitamin D levels.

Read more about the sun and Vitamin D.


Am I at risk of sunburn today?

Although 11am to 3pm is when the sun’s UV rays are strongest in the UK, this can differ depending on where in the world you are. Always check the UV index to find out how strong the sun is on any given day.

What times of year can you get sunburnt? 

The highest risk months in the UK are March to October.

Can you get sunburnt when its cloudy?

Clouds block some UV, but over 90% can still pass through light cloud and cause sunburn.

Where are you most likely to get burnt?

Near the equator, there are strong UV rays all year round. UV rays are also stronger at higher altitudes. So skiers and mountaineers can easily get caught out.

Can UV rays be reflected?

Up to 85% of UV rays are reflected back from snow, 15% from sand and 10% from water.


National Institute for Health and Care Excellence (NICE). Sunlight exposure: risks and benefits. [Accessed June 2021]

World Health Organisation. Global Solar UV Index A Practical Guide. [Accessed June 2021]

International Agency for Research on Cancer. Radiation. Vol 100; 2012.

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