New Zealand's rather cool and temperate temperatures can easily hide the harmful effects of the sun. Yet in any season and any weather, the New Zealand sun can burn. Many people say they get more sunburned in New Zealand than anywhere else in the world, even Australia!
In terms of energy, the sun is stronger in Australia due to it being closer to the equator. But in terms of UV light which causes sunburn, it is stronger in New Zealand due to a thinner ozone layer, and less pollution (clearer air).
New Zealand has naturally high UV levels compared with similar latitudes. For example, our peak UV levels can be 40 percent higher than peak UV levels in similar North American latitudes (McKenzie et al, 2006).
At mid-latitudes, such as New Zealand, it is thickest during spring and thinnest during autumn. This means the ozone layer over New Zealand thins during summer, providing less protection from UV sunlight when we are closest to the sun and the sun is highest in the sky.
In New Zealand, its maximum summer value is generally about 12, but it can exceed 13 in the far North. In winter it reaches peak values of 1 or 2. Values of 10 or more should be considered as "extreme". At high altitude tropical sites (eg Mauna Loa Observatory, Hawaii), the UV Index can exceed 20.
There is a strong latitudinal gradient UVI. Consequently, 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.
The highest UVI of 25 was in the grid cell centred on Cuzco, in southern Peru (13.5° S, 3360 m a.s.l.). Peak values on the edge of the Antarctic Plateau also exceed the highest UVI in New Zealand, and are comparable to those at sea level in the tropics.
Australia's unusually harsh sunshine results mainly from its location in the Southern Hemisphere. The elliptical orbit of the Earth places the Southern Hemisphere closer to the sun during its summer months than the Northern Hemisphere during its summer.
As general guide, the Cancer Society of NZ recommends the use of broad-spectrum, SPF30+ sunscreen. Broad-spectrum sunscreen gives extra protection because it filters out both UVA and UVB rays. UVA causes ageing of the skin and long-term damage.
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 11 minutes on a fine summer day. UV radiation from the sun is also one of the best natural sources for vitamin D so a balance is important.
It is possible to get sunburnt in a very short time. When UV radiation levels are high, damage to people with light coloured skin can occur in as little as 12 minutes. Check the Sun Protection Alert, NIWA UV forecasts, and UVNZ app for details about the time each day that you need to protect your skin and eyes.
UV problem of another kind
"Tasmania is unique with the fact that in summer it gets to extreme level, and in winter it doesn't even get to moderate," Mr Carr said. "A few places on the mainland get below 3 in winter, but Tasmania — the whole island — struggles to get to 2 or 2.5, even on a sunny day."
New Zealand's climate is milder, colder, and wetter – which could be a positive or a negative, depending on your preferences. Of course, if you're hoping for a warm to hot climate, Australia is definitely your pick; though be warned, the summer months bring intense heat waves and humidity.
Australia is warmer than New Zealand, with a summer average of 30°C and winter average of 15°C. New Zealand, is a touch cooler, with a summer average around 20 to 25 degrees and a winter average around 12°.
Australia experiences some of the highest levels of UV radiation in the world because we are close to the equator and have many clear, blue-sky days.
UVB rays, which affect skin's top layer, cause skin cancer and most sunburns. Although UVA and UVB rays pose the greatest risk for sun damage, people who work with welding torches or mercury lamps may be exposed to UVC rays — the most dangerous type of UV radiation.
Oodnadatta, South Australia
The record for the highest official temperature ever recorded in Australia belongs to the remote outback town of Oodnadatta in South Australia.
The ozone layer is depleted in two ways. Firstly, the ozone layer in the mid-latitude (e.g. over Australia) is thinned, leading to more UV radiation reaching the earth. Data collected in the upper atmosphere have shown that there has been a general thinning of the ozone layer over most of the globe.
During summer, the Earth's orbit brings Australia closer to the sun (as compared to Europe during its summer), resulting in an additional 7% solar UV intensity. Coupled with our clearer atmospheric conditions, this means that Australians are exposed to up to 15% more UV than Europeans.
Norway. Norway, situated in the Arctic Circle, is called the Land of the Midnight Sun, where from May to late July, the sun actually never sets. This means that for around a period of 76 days, the sun never goes down.
Protection is required when UV radiation is damaging (when UV levels are 3 or higher).