About UV radiation

Ultraviolet (UV) radiation is a type of energy produced by the sun and some artificial sources, such as solariums. UV radiation is not part of the visible spectrum of light, nor is it thermal radiation or heat – unlike sunlight it cannot be seen, nor can it be felt like the sun’s warmth.

Overexposure to ultraviolet (UV) radiation from the sun is the major cause of skin cancers. Little can or should be done to change the levels of solar UV radiation, instead we need to reduce our UV exposure and therefore, hopefully, subsequent skin cancers.

Australia has some of the highest levels of UV radiation in the world – in fact, UV radiation is strong enough to cause sunburn in as little as 10 minutes on a fine January day.

UV radiation is divided into three types, categorised by wavelength: UVA, UVB and UVC.

While all UVC radiation is absorbed by the atmosphere, all UVA and about 10 per cent of UVB radiation does reach the Earth’s surface.

  • UVA can cause sunburn, DNA (cell) damage in the skin and skin cancer.
  • UVB causes skin damage and skin cancer.
  • UVC is the most dangerous type of UV. Ozone in the atmosphere absorbs all UVC and it does not reach the earth’s surface.

Factors affecting levels of UV radiation

UV radiation can reach you on the ground directly from the sun. It can also be scattered by particles in the air and reflected by ground surfaces such as metal, concrete, sand and snow.

Levels of UV radiation are also affected by:

  • Sun elevation — the higher the sun is in the sky, the higher the levels of UV radiation at the Earth’s surface. Therefore, levels of UV radiation are highest in the middle of the day, and during summer months.
  • Latitude — the closer to the equator you are, the higher the levels of UV radiation.
  • Cloud cover — UV radiation can pass through light cloud cover, and on lightly overcast days the intensity of UV radiation can be similar to that of a cloud free day. Heavy cloud can reduce the intensity of UV radiation. Scattered cloud has a variable effect on levels of UV radiation, which rise and fall as clouds pass in front of the sun.
  • Altitude — at higher altitudes, the atmosphere is thinner and absorbs less UV radiation.
  • Ozone — ozone absorbs some of the UV radiation that would otherwise reach the Earth’s surface.

The UV Index, a rating system adopted from the World Health Organization, describes the amount of UV radiation at the Earth’s surface.

The UV Index

The UV Index is a standard and useful measure scale which tells us how strong the UV is and how to protect ourselves accordingly. Whenever the UV is 3 or above, sun protection is required. The higher the level, the shorter time it takes for skin damage to occur.

Sun protection times

Sun protection times are a daily time period showing when UV levels are predicted to be 3 or above, and sun protection is needed. The sun protection times vary according to your location and will change throughout the year.

Understanding UV – How to read the UV forecast

Download the free SunSmart Global UV app

Our free SunSmart Global UV app puts sun protection advice at your fingertips, provides reliable at-a-glance real-time and forecast UV levels for locations across Australia and the world from reputable and trusted agencies and translates this data into clear, evidence-based health advice from Cancer Council Victoria to recommend sun protection for your location.

Download for iOS Download for Android

Five facts about UV

In Australia, we’re exposed to some of the harshest and most dangerous levels of ultraviolet (UV) radiation in the world.

In most parts of Australia, the UV Index reaches 11 or more in the summer – but you may still need to be SunSmart in winter too.

In summer, most of Australia has average clear-sky maximum UV forecasts in the ‘extreme’ range (11+). But even as temperatures drop in winter, the UV Index often reaches 3 or above. Don’t be fooled by temperature – check the UV Index and be SunSmart when it is 3 and above.

You get sunburnt fastest when your shadow is shortest.

When the UV is high, the sun is also high causing it to case a shorter shadow. UV peaks at solar noon (around midday), so protecting your skin in the middle of the day is particularly important.

Too much UV can lead to DNA damage to skin cells.

UV radiation can cause sunburn, eye damage, premature aging and skin cancer. This DNA damage can’t be undone and adds to your lifetime tally of UV damage, increasing your skin cancer risk and eye damage such as cataracts and ocular melanoma.

UV radiation is invisible and can’t be felt.

Heat is caused by infrared radiation, not UV radiation. It can be a cooler day with extreme levels of UV – don’t be fooled by temperature when it comes to preventing sunburn and future skin cancers!

The majority of the visible signs of aging to the skin are the result of damage from UV exposure.

It is believed that as much as 80% of premature facial ageing – such as wrinkles, loss of skin tone, elasticity and fine lines – is due to sun exposure.

UV Index widget

Take away the guesswork of daily UV by adding the free SunSmart widget to your website

Get the widget

Download SunSmart resources

Cancer Council WA have a range of free resources to download and order.

Explore resources to download

UV readings from around Australia

Browse other locations

Western Australia

New South Wales

Forecast Data