7 things you didn't know about the UV Index + how to check it

7 things you didn't know about the UV Index + how to check it

Posted by Gina Russell on

Most people tune in to the weather report or check the forecast on a daily basis, but have you ever checked the UV Index? 

Here we'll take you through some important questions about the UV Index and arm you with some great ways to check and use this index in your daily routine.

What is the UV Index?

Definition: The UV Index is an international, scientific measure of the level of UV radiation from the sun.  The UV Index is based on erythemally weighted irradiances (i.e. sun-burning irradiances), published by NIWA. The higher the number on the UV Index, the higher the radiation level.

Essentially, the UV Index is the measure of the radiation from the sun that impacts at ground level. It is used globally which helps researchers understand local requirements compared to other countries and also helps travelers prepare for the change in UV strength.

See this link to learn more about the UV spectrum.

Why is it so important?

The UV Index is important for New Zealand because we have one of the largest rates of melanoma incidence in the world with annual death rates exceeding those of our national road toll. Melanoma is understood to be directly related to sun exposure and can occur in those who have had more than 5 sunburns over their lifetime. 

In order to address this issue, organizations around the country have been putting an emphasis on educating the population about sun care (Slip, Slop, Slap for example), making it mandatory in primary schools and raising awareness around understanding your skin through regular spot checks.

See this link to learn more about Melanoma in New Zealand.

What does the UV Index NOT tell us?

The UV Index is a great tool in your atmospheric awareness arsenal but it's not the be-all and end-all. Other information you might need on a daily basis may include the expected temperature, pollution levels in your area, reflection/amplification of the suns rays (from sand, water, glass etc), your particular burn time or your personal risk of developing melanoma

Being aware of your personal skin needs as well as your surroundings and taking action to ensure your skin is well cared for is and should be your top priority. Talking with your skincare professional will help you decipher what actions and care your particular skin needs. 

At what level should I be concerned?

It's advisable to wear sunscreen at level 3 and above. During the summer months in New Zealand, we can reach an index level of 3 as early as 8:30 in the morning! So being aware of what the UV level is expected to do throughout the day will not only help you time your sunscreen application, but also plan your day so that you're avoiding the sun during very high UV levels.

What should I be doing at each level?

The diagram below will help you understand the basics of sun protection throughout the day but also knowing your skin type and how your skin reacts in the sun is just as important because everybody is different.

All about the UV Index
Warning - Using this tool for optimal sun-tanning is not recommended. Please practice safe-tanning by visiting your local spray-tanning salon. 

Where does NZ sit on the global UV scale?

UV in New Zealand is relatively high compared with corresponding northern latitudes, due to its lower summer ozone amounts, closer Earth-Sun separation in summer, and unpolluted air. We're often in the higher percentage of countries that reach a UV Index above 10, however the stats are interesting. For example:

  • The UV scale was first used in Canada and defined to range from 1 to 10 there. In the NZ summer, UVI values regularly exceed 13.
  • A recent study showed that peak UVI values in NZ are about 40% more than at similar latitudes in North America.
  • Compared with equatorial regions, our UV is not particularly strong, with factors such as altitude, snow reflection, pollution, ozone levels etc all having an effect.
  • The mean UVI in New Zealand is significantly less than in Australia, but is about twice as much as in the UK, which spans a range of much higher latitudes. 

You can learn more about global levels here.

How do I check the UV Index?

There are many ways to check the UV Index, and looking out the window is NOT one of them!

  • NIWA website - NIWA provides New Zealanders with a daily UV forecast alongside the weather forecast 
  • Metservice website - Metservice also show the sun protection alert on their regional forecast pages
  • SunSmart website - Sunsmart is New Zealand's go-to organization for anyone wanting to learn about sun protection
  • Phone apps! Yes, we can now check the UV levels in our pocket. Here's a couple of apps to check out:


We hope this has answered some questions and helped you learn a bit more about the sun and how to protect yourself from it. For more information about the UV index and how it's measured in New Zealand, visit NIWA's website. You can also download a copy of the INTERSUN (WHO's UV project) guide here.


Science Suncare

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