About Forecasts for Sun Safety

What is the UV Index?

The UV Index is a simple and informative way of describing the daily danger of solar UV radiation intensity. Each point on the Index scale is equivalent to 25 milliWatts/square metre of UV radiation. 

Types of UV Index forecasts

The UV Index forecast is issued in four types of formats. It is presented as a map of Australia as well as graphs and text tables for over 200 cities and towns. A plain text version is also available on the Bureau’s FTP site. The graphs and text UV Index forecasts include the SunSmart UV Alert. All the forecasts can be accessed from the UV Index home page.

UV Index forecast chart for Australia

UV Index forecast graphs for cities & towns

UV Index text forecasts for cities & towns

What is the UV Alert?

The UV Alert is issued when the UV Index forecast is 3 or above, a level that can damage your skin and lead to skin cancer. The higher the Index value, the greater the potential for damage to your skin. The UV Alert shows the time of the day people need to be SunSmart.

The UV Alert is an initiative of The Cancer Council Australia, the Bureau of Meteorology and the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA). It is based on the World Health Organisation's Global Solar UV Index.

The UV Alert can be found on the weather page of most Australian daily newspapers. SunSmart UV Alerts are linked from the forecast pages for each state and territory as well as the UV Index home page.

How to read the UV Alert

This shows the period of this day that you need to be SunSmart 8.15 am - 4.20 pm.

UV Index range:

• Low (0-2)
• Moderate (3-5)
• High (6-7)
• Very High (8-10)
• Extreme (11+)

UV Radiation – the invisible killer

Australia has the highest incidence of skin cancer in the world. More than 1400 Australians die from skin cancer each year, and 1 in 2 people will get skin cancer in their lifetime.

Ultraviolet (UV) radiation is the invisible killer that you can’t see and you can’t feel. Heat or high temperatures are not an indication of UV radiation.

5 steps to be SunSmart

The Cancer Council Australia recommends Australians take five steps to protect against sun damage when the SunSmart UV Alert indicates the UV Index is at 3 or above:

Check and Protect

It is important for all Australians or visitors to Australia, to look and listen for UV Index levels in local weather forecasts.

1. Slip on some sun-protective clothing - that covers as much skin as possible
2. Slop on SPF30+ sunscreen - make sure it is broad spectrum and water resistant. Put it on 20 minutes before you go outdoors and every two hours afterwards. Sunscreen should never be used to extend the time you spend in the sun.
3. Slap on a hat - that protects your face, head, neck and ears
4. Seek shade
5. Slide on some sunglasses - make sure they meet Australian Standards
   

Remember, you should use a combination of sun protection measures to keep you safe from UV radiation-never rely on just one.

For more information about being sun smart, visit SunSmart: www.sunsmart.com.au

The maximum UV Index level forecast for this day is 12 - which is extreme.

Shows the time of day.

Facts about UV Radiation

• The sun emits UVA, UVB and UVC radiation. The ozone layer blocks all UVC radiation, most UVB but none of the UVA radiation.
• UVA penetrates deep into the skin causing damage like wrinkles and discolouration.
• Exposure to UVB causes sunburn. Sunburn, whether severe or mild, can cause permanent skin damage.
• Skin cancer is a disease of the body’s skin cells caused mainly by overexposure to UV radiation.
• Heat or high temperatures are not an indication of UV levels.
• Factors such as latitude, ozone, cloud, reflection from surfaces, time of year and time of day determine UV levels.
• UV levels vary in intensity and level across Australia on any given day.
• When the UV Index reaches 3, sensible sun protection is warranted and is unlikely to put people at risk of Vitamin D deficiency.

Calculating the danger

A computer model is use to forecast the UV radiation at ground level. It takes into account information on the time of day, date, latitude, altitude and ozone concentrations.

The maximum UV Index is calculated for midday assuming cloud-free skies. Values are also calculated for cloudy and overcast skies. Both clear-sky and cloud affected UV Index values are included in the tabular forecast, while only clear sky values appear in the chart and graphs.

Cloudy days deceive many people into thinking the danger of UV radiation is minimal.
Most clouds block some UV radiation, but the degree of protection depends on the type and amount of cloud. Some clouds can actually increase the UV intensity on the ground by reflecting and refracting the sun's rays. People can also be caught unawares when a small break in an overcast deck of clouds allows a brief burst of intense radiation to reach the ground.

Cold air can also be deceptive as temperature is not directly related to UV intensity. Skiers should take particular care as reflective snow on the ground and high altitude raise the UV Index significantly relative to its value at sea level.

For further information contact the Bureau of Meteorology
or The Cancer Council Australia in your State or Territory (Phone 13 1120).

World Health Organisation Intersun Global UV project website www.who.int/uv/en/

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