Sunburn danger this weekend

New Zealand will suffer a record "low ozone event" for spring on Sunday meaning people could burn even if the weather is cool, climate scientists are warning.

Niwa said space agencies are forecasting that there could be 23 per cent less ozone over New Zealand than the average for this time of year, making it highly likely people could burn if the weather is good.

The forecast comes from the Royal Dutch Meteorological Institute and the European Space Agency. They say a sliver or filament of low ozone air circulating in the stratosphere around Antarctica will spin off and pass over much of New Zealand.

"Ozone values of about 275 Dobson Units are possible, whereas the September average at Lauder, Central Otago, is 358 Dobson Units,' says Dr Greg Bodeker of the National Institute of Water & Atmospheric Research.

"The forecast suggests that the ozone values around noon on Sunday are likely to be a record low for this time of the year,' says Dr Bodeker.

New Zealand ozone records began in 1970.

The forecast low ozone will push UV levels higher than usual for this time of year.

Wendy Billingsley, a spokesperson for SunSmart, says protection will be essential if the day is clear or partly cloudy.

Protection is essential when UV levels reach 6. According to Niwa, if the skies are clear, the forecast low ozone means that UV levels in the south of New Zealand are likely to increase from a typical September noon-time UV index of 4 to 5.5.

In the north of the country, the noon UV index could be as high as 8 compared to the usual September value of around 6.5.

At southern ski fields, where the snow-covered surface enhances UV levels, the reduced ozone could cause noon-time UV levels to increase from 6 to close to 8.

A UV index of 8 represents very high UV levels, though not the levels reached on a sunny summer day.