UV index
How to read the daily UV number, what each band means and when health bodies advise you to cover up.
The UV index is a scale that shows how strong the sun's ultraviolet (UV) radiation is at a given place and time. The higher the number, the greater the potential for damage to your skin and eyes, according to the World Health Organization (WHO). Forecasts usually quote the day's peak, which WHO says occurs during the four hours around solar noon.
What do the UV index numbers mean?
Each reading falls into one of five bands, from low to extreme. These are the bands Cancer Council Australia uses:
| Band | UV index |
|---|---|
| Low | Up to 2 |
| Moderate | 3 to 5 |
| High | 6 to 7 |
| Very high | 8 to 10 |
| Extreme | 11 and above |
What UV index is safe to be outside without protection?
Sun protection is advised whenever the UV index is 3 or higher. WHO notes that below 2 the risk of UV damage is limited, even for very sensitive fair skin, and recommends protective measures from 3 upwards. At 8 and above, it advises avoiding time outside during the midday hours. In Australia, the Bureau of Meteorology issues sun protection times for the hours when the index is forecast to reach 3 or more, as Cancer Council Australia explains. For what this means for clothing, see UPF.
Can the UV index be high on a cloudy day?
Yes. Cancer Council Australia points out that UV radiation can be high even on cool and overcast days. Temperature and brightness are poor guides, so it is worth checking the index itself before you head out for the day.
Where can you check the UV index?
It is usually reported with the weather. WHO notes that the index appears alongside forecasts in newspapers, on television and radio, and in websites and apps. In Australia, ARPANSA publishes live readings from detectors in cities around the country, which respond to UV in a similar way to human skin and update every minute. You can see how strong it gets in each month in more than 100 cities on our UV and heat pages, and read more in the UV index explained.