SunticWhat is the UV Index?
The UV index is a simple number that tells you how strong the sun's ultraviolet (UV) radiation is at a given place and time. It runs from 0 upwards, and the higher it is, the faster unprotected skin can burn. It was developed by scientists in Canada and is now standardised worldwide by the World Health Organization (WHO) and the World Meteorological Organization.
What does the UV index actually measure?
The index estimates the amount of skin-damaging UV reaching the ground, weighted for how much harm different wavelengths cause. Two types of UV reach us: UVA (linked to ageing) and UVB (the main cause of sunburn). The UV index reflects the burning potential of both, so a higher number means a higher risk of damage in a shorter time.
Crucially, the UV index is local and time-specific. It changes with the time of day, the season, your latitude and altitude, cloud cover, and reflective surfaces like snow, water and sand. That's why the only meaningful reading is one for your exact location, like the live value in the Suntic app.
What do the UV index levels mean?
The WHO groups the index into five risk bands. Here's what each one means and what to do:
0-2 (Low): Minimal risk. You can safely be outside; wear sunglasses on bright days.
3-5 (Moderate): Take care around midday. Use SPF 30+, a hat and shade.
6-7 (High): Protection needed. Cover up, use SPF and seek shade from late morning to mid-afternoon.
8-10 (Very high): Minimise sun exposure at midday; sunscreen, clothing and shade are essential.
11+ (Extreme): Take every precaution. Unprotected skin can burn very quickly.
For a deeper breakdown of every level, see our guide to the UV index 1 to 11 explained.
Why does the UV index matter more than temperature?
It's a common mistake to judge sun risk by how hot it feels. UV and heat are not the same thing. You can get a serious burn on a cool, breezy spring day when the UV index is high, and you can be comfortable on a hot day with relatively low UV. Going by the index rather than the temperature is the single biggest upgrade you can make to your sun habits.
How do you use the UV index every day?
- Check the index for your location before you head out: a glance at a widget is enough.
- Match your protection to the number: the higher it is, the more shade, clothing and sunscreen you need.
- Plan around the peak. UV is usually strongest from about 10am to 4pm, so schedule intense activities earlier or later.
- Re-check during the day, because the index rises toward solar noon and falls again afterwards.
Suntic does this for you automatically: it reads the real-time UV index for your location, shows a 10-day forecast, and translates the number into a personalised safe-sun time based on your skin type and SPF.
Frequently asked questions
What is a good UV index?
A UV index of 0-2 is low and considered safe for most people with minimal precautions. From 3 upwards, sun protection is recommended, and 8 or above is very high risk.
What UV index will give me a tan?
Any UV index above about 3 can produce a tan, but it also brings a risk of burning and skin damage. There is no UV level at which tanning is risk-free. See our guide on tanning more safely.
Is UV index 6 high?
Yes. UV 6-7 is classified as 'high'. Unprotected skin can burn within a relatively short time, so cover up, use SPF 30+ and seek shade around midday.
