The UV Index Scale, & When To Layer Your SPF, Explained

You’ve probably spotted that little number next to the sun icon on your weather app, the UV Index.

Some days it’s a chill 2. Other days it’s a screaming 9 or even 11+. But what do those numbers actually mean? And when should you be layering on the SPF like your life depends on it? (Spoiler: most days.)

Here’s your no-BS guide to what the UV Index really means, and why it really matters. Especially if you want to avoid turning into a human lobster this summer.

0-2: Low Risk

You’re safe to be outside without any major worry. If you’re heading out for hours or have fair skin, a bit of SPF doesn’t hurt (it never does btw), but this is the range where you can romanticise your morning walk without frying your face. Enjoy it.

3-5: Moderate Risk

Okay, now we’re talking. At this level, UV rays are strong enough to start damaging your skin, especially if you’re out between 11am and 3pm. SPF 30+ is your bestie, and if you’re planning a picnic or outdoor brunch, bring sunglasses and maybe a cute hat. Chic and sun safe.

@lucyvelastegui okay i lowkey get tan lines in winter so it’s a great use of my time #tanning #california #foryoupag ♬ original sound – Hey Bud Skincare

6-7: High Risk

This is where things get real. Your skin can burn in about 20 minutes, especially if you’re fair or have been on the couch all winter (hello, most of us in Ireland). You’ll want a good SPF 50, reapplying every couple of hours, and some legit shade if you’re out midday. This is not a drill.

8-10: Very High Risk

These levels are no joke. UV rays are strong enough to cause serious skin and eye damage, even if it’s cloudy (yes, seriously). Sunburn can happen FAST. Think SPF, sunnies, wide-brimmed hats, and shady spots. Cancel that sunbathing session and opt for iced coffee in the shade instead. It’s just as fun.

@ari.lansden don’t worry it turned tan over night #tanning ♬ original sound – jbisakol – undftdapparelph

11+: Extreme Risk

Yes, this exists and it is insanely dangerous! At this level, just stepping outside without protection can damage your skin and eyes in minutes. SPF 50+, sunglasses with proper UV protection, and covering up with clothes are essential. If you can, just avoid direct sun altogether from late morning to mid-afternoon. Though it’s very rare to witness.

Reminder: UV Isn’t Just a “Beach Day” Thing

Even if the sun doesn’t feel hot or you’re just walking to the shop, UV rays are still doing their thing. Damage builds up over time, even on cloudy days. So yes, daily SPF is the grown-up hot girl habit that future you will thank you for.

Bottom line? If you’re checking the weather, check the UV too. Your skin will thank you, immediately and in ten years when you’re still glowing with flawless skin.

Words by Emilia Cercel