SunticUV Index 1 to 11+ Explained
The UV index runs from 0 upwards on an open-ended scale, with most places topping out somewhere between 0 and 11, and a handful of extreme locations going higher. The World Health Organization splits the scale into five colour-coded risk bands so you can tell at a glance how much protection you need. Below we walk through each band, what the number means for your skin, and the practical steps that go with it.
0 to 2: Low
Low UV. The risk of harm from unprotected sun exposure is minimal for the average person. You can comfortably spend time outdoors without special precautions, though sunglasses are worth wearing on bright days and around reflective snow or water. This is the typical range early and late in the day, in winter at higher latitudes, and under heavy cloud.
3 to 5: Moderate
Moderate UV. There is a genuine risk of harm around the middle of the day. Apply broad-spectrum SPF 30+ to exposed skin, wear a hat, and take to the shade during the strongest hours. This band is common on spring and autumn days, and even fair skin can avoid trouble here with a few simple habits.
6 to 7: High
High UV. Protection is needed, not optional. Unprotected skin can start to burn within a fairly short time, so cover up with clothing, use sunscreen and seek shade from late morning to mid-afternoon. Summer days in much of the world fall into this band, and it's where careless sun habits start to cause real damage.
8 to 10: Very high
Very high UV. The risk of rapid harm is serious. Minimise time in direct sun during the midday hours, and treat sunscreen, protective clothing and shade as essential rather than as a backup. Reapply sunscreen often, especially after swimming or sweating. This band is typical of bright summer days in sunny climates and at lower latitudes.
11+: Extreme
Extreme UV. Unprotected skin can burn very quickly indeed. Take every precaution available: cover as much skin as possible, stay out of direct sun during the peak, and rely on shade wherever you can find it. You'll mainly meet this band in the tropics, at high altitude, and near strongly reflective surfaces.
Why does your skin type change everything?
The bands above describe the strength of the UV, but how quickly your own skin reacts depends heavily on your skin type. The amount of melanin in your skin offers some natural protection, so very fair skin that burns easily will reach its limit far sooner than darker skin at the same UV index. That means the same reading of 6 can be moderately risky for one person and quite dangerous for another.
Importantly, everyone is at some risk, even people who rarely burn, because UV still drives ageing and longer-term harm regardless of how your skin looks afterwards. For a fuller picture of how the index relates to your own skin, see our guide on what the UV index means for your skin. Suntic accounts for this by translating the live index into a personalised time based on your skin type.
When will you see extreme UV?
Most people rarely see the top of the scale, but certain situations push the index much higher than you might expect. Altitude is a big one: UV climbs noticeably as you go up a mountain because there's less atmosphere to filter it. The tropics sit closer to the sun's most direct angle, so midday readings there can reach extreme levels even outside summer.
Reflective surfaces add to the effect. Fresh snow can bounce a large share of UV back at you, which is why skiers and climbers can burn badly, and water and white sand do the same on a smaller scale. If you're heading somewhere bright, high or near snow and water, check the UV index for today before you set out rather than assuming it matches home.
Frequently asked questions
What is the highest the UV index can go?
The scale is open-ended, but in practice most places peak between 0 and 11. Readings above 11 are classed as 'extreme' and occur mainly in the tropics, at high altitude, or near reflective snow and water.
Is UV index 3 dangerous?
A UV index of 3 is the start of the 'moderate' band, where protection becomes worthwhile. It isn't extreme, but applying SPF 30+ and using shade around midday is sensible, especially for fairer skin.
Does the UV index account for my skin type?
The standard scale measures UV strength, not personal risk. Your skin type changes how fast you react, which is why the Suntic app converts the live index into a time tailored to your skin.
