The UV index, explained
The UV index measures how strongly the sun can burn your skin. It runs from 0 to 11 and higher, and sun protection is recommended from 3 up.
The five UV categories
LowUV 0 to 2
Minimal risk for most people. Protection only for long periods outside.
ModerateUV 3 to 5
Protection starts here. Unprotected skin can burn in under an hour.
HighUV 6 to 7
Burns come quickly. Hat, sunscreen and shade around midday.
Very highUV 8 to 10
Every form of protection, and shade from 11am to 3pm.
ExtremeUV 11+
Common in the north. Avoid the midday sun where you can.
How the UV index is measured
Sensors measure sunlight across the UV wavelengths that burn skin, then weight each wavelength by how much damage it does. ARPANSA runs a network of these sensors in every capital city. Forecasts combine the sun’s angle, ozone and cloud to estimate the index hour by hour for places without a sensor.
Why UV runs high in Australia
Australia sits under clear, dry air with relatively low ozone overhead. In January the Earth is also closest to the sun, which adds around 7% more UV to a southern summer than a northern one.Why UV is so high in Australia
FAQs about the UV index
- What is a good UV index?
- Below 3 is Low, and most people can be outside for a while without sun protection. From 3 up, protect your skin with a hat, sunscreen, clothing, shade and sunglasses.
- What is the highest the UV index goes?
- The scale has no top. In Australia, summer readings of 12 to 14 are common in the north, and readings above 15 happen in the tropics and at altitude.
- Is the UV index the same as the temperature?
- No. UV is a kind of sunlight you can’t see or feel, so a cool, clear spring day can have higher UV than a hot evening. Check the UV index, not the thermometer.
- Why does the UV index change during the day?
- It follows the sun’s height in the sky. UV is lowest early and late, and highest around solar noon, which falls around 1pm in daylight saving time.