UV index scale
The UV index scale runs from 0 to 11 or more. 0–2 is low, 3–5 moderate, 6–7 high, 8–10 very high and 11+ extreme. Sun protection is recommended from 3 upward, and the higher the number, the less time it takes unprotected skin to burn.
The five levels
Low
Most people can be outside safely. Sunglasses help on bright days, and anyone who burns easily should still cover up. Snow and sand reflect UV and raise exposure.
Moderate
Seek shade around midday, wear a hat and sunglasses, and use a broad-spectrum SPF 30 or higher sunscreen on exposed skin.
High
Cut back on time in the sun between 10 a.m. and 4 p.m. Cover up, use sunscreen, wear sunglasses and seek shade.
Very high
Unprotected skin and eyes can burn quickly. Avoid midday sun, seek shade, cover up and reapply sunscreen about every two hours.
Extreme
Unprotected skin and eyes can burn in minutes. Avoid the sun during midday hours and take every precaution.
How to use the scale
Check the day’s peak UV index before you head out, then plan around the midday hours when it is highest. A forecast of 3 or more means it is worth wearing sunscreen, a hat and sunglasses and taking breaks in the shade.
The same number can feel very different depending on skin type, altitude and what you are standing on. Snow, water and sand reflect UV and can raise your exposure.
Questions
What UV index is safe?
There is no UV level that is completely risk-free, but a UV index of 0–2 is considered low risk for most people. At 3 or above, sun protection is recommended.
Does the UV index depend on temperature?
No. UV is invisible radiation, not heat. You can get a high UV index on a cold, sunny day, especially around snow.
Is a UV index of 11 the maximum?
No. The scale is open ended, and 11+ is labelled extreme. Values above 11 occur in the tropics and at high altitude.
Source: U.S. EPA SunWise and the UV Index; World Health Organization, Global Solar UV Index: A Practical Guide. Last reviewed 2026-10-27.