UV index 11+: how long until skin burns?
UV index 11+ falls in WHO's Extreme category. Without protection, very fair skin (type I) can start to redden in under 10 minutes, and olive skin (type IV) in about 25 minutes. These are rough estimates, not safe times.
Extreme · 11+ Highest level: avoid midday sun; full protection for everyone.
A warning, not a safe time. Redness shows up hours later.
Minutes to first redness by skin type
| Type IAlways burns, never tans; very pale skin, often freckles or red hair | under 10 minutes |
|---|---|
| Type IIUsually burns, tans with difficulty; fair skin, often light eyes | about 10 minutes |
| Type IIISometimes burns, tans gradually; light to light olive skin | about 20 minutes |
| Type IVRarely burns, tans easily; olive or light brown skin | about 25 minutes |
| Type VVery rarely burns, tans darkly; naturally brown skin | about 35 minutes |
| Type VIAlmost never burns; naturally dark brown to black skin | about 60 minutes |
What WHO advises at this level
This is the highest WHO category. Avoid the midday sun, stay in the shade, and wear a shirt, a broad-brimmed hat, wrap-around sunglasses and sunscreen on any skin left uncovered. Unprotected fair skin can start to redden in under 10 minutes, and olive skin in under half an hour. Keep babies out of direct sun and take special care with children.
When and where you see this level
UV 11 or more is normal in the tropics for much of the year, in Australia and the Gulf states in summer, and high in the Andes or Himalayas. Values of 12 to 14 are common there; some mountain sites exceed 20.
What this means if you want a tan
At UV 11 and above, unprotected fair skin can start to redden in under 10 minutes and even olive skin in under half an hour. There is no safe tanning time at this level. Stay in shade around midday and cover up fully.
Frequently asked questions
How long does it take to burn at UV 11+?
Rough estimates for unprotected skin at UV 11+: type I: under 10 minutes; type II: about 10 minutes; type III: about 20 minutes; type IV: about 25 minutes. Redness usually appears hours later, and some people burn sooner. These are not safe times.
Is UV 11+ high?
Extreme (11+). This is the highest WHO category. Avoid the midday sun, stay in the shade, and wear a shirt, a broad-brimmed hat, wrap-around sunglasses and sunscreen on any skin left uncovered. Unprotected fair skin can start to redden in under 10 minutes, and olive skin in under half an hour. Keep babies out of direct sun and take special care with children.
Can you tan at UV 11+?
At UV 11 and above, unprotected fair skin can start to redden in under 10 minutes and even olive skin in under half an hour. There is no safe tanning time at this level. Stay in shade around midday and cover up fully.
Sources
- WHO, WMO, UNEP, ICNIRP (2002): Global Solar UV Index – A Practical Guide
- WHO (2022): Radiation – The ultraviolet (UV) index, questions and answers
- ICNIRP with ILO and WHO (2007): Protecting Workers from Ultraviolet Radiation (skin types and SED, Table 1)
- Journal of Cosmetic Dermatology: Fitzpatrick skin phototypes with typical minimal erythema dose (Table 1, after Fitzpatrick 1988 and Pathak 1987)
- CIE: Standard Erythema Dose, a Review (1 SED = 100 J/m²)