How to Read the UV Index

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The Five Risk Zones (WHO Color Scale)

The WHO UV scale is divided into five risk zones, each with a standard color: LOW (0-2, green) — minimal risk, no special protection needed for most people. MODERATE (3-5, yellow) — seek shade during midday, use SPF 30+ if outdoors for extended periods. HIGH (6-7, orange) — reduce time in the sun from 10am-4pm, wear SPF 30+, protective hat, and sunglasses. VERY HIGH (8-10, red) — take extra precautions, SPF 50+, full protective clothing recommended, minimize midday outdoor time. EXTREME (11+, violet) — take all precautions, avoid outdoor activities at midday if possible, maximum protection at all times.

Try it in the app:

In SunUp, notice the colored band around the UV number and the risk label beneath it. This matches the WHO scale exactly.

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Pro tip:

In Australia, UV 11+ is common. In Canada, UV 8-9 is typical on summer afternoons. In the tropics, UV 13-14 is not unusual.