Turning the clock forward to enjoy longer days should jog people's memories that more sun means a higher exposure to ultraviolet (UV) rays.
Richard McKenzie of the National Institute of Water and Atmospheric Research (Niwa) said now the sun was staying higher in the sky, its rays had
a shorter distance to travel to earth.
"The shorter the distance the rays have to travel, the less ultraviolet radiation is absorbed by gases in the atmosphere - like ozone - and the more radiation hits earth."
He said with UV rays peaking in the summer, people were being urged to protect themselves from the harmful effects of the sun, while still enjoying the outdoors.
Health Sponsorship Council's SunSmart manager Wayde Beckman said over-exposure to the sun's ultraviolet radiation was the cause of over 90 per cent of all skin cancer - making prevention crucial.
"At this time of year, even if the day is cloudy remember the SunSmart message - slip, slop, slap and wrap.
"Never get sunburnt and always make sure you have protective gear on, such as a shirt with collar and long sleeves. Slip into the shade, slop on some sunscreen, slap on a hat and wrap on a pair of sunglasses."
Dr McKenzie said because the sun elevation angle was a strong indicator of UV intensity, an easy way of judging how high the UV radiation was likely to be was by observing the length of your shadow.
"As your shadow gets shorter, you know the UV risk is getting bigger.
"If your shadow is less than twice the length of your body, there is a risk of damage from UV. At this time of year, your shadow length at midday is about the same length as your body and it will get shorter each day as summer approaches."
- NZPA
