Youngsters are being encouraged to seek shade when the sun makes a rare appearance this summer.
Despite the heavy downpours beleaguering the British summer, the brief spells of sunshine can be strong and can cause skin damage, cancer experts warned.
Cancer Research UK called for young people to protect their skin from harmful UV rays.
Research conducted by the charity found that although 80% of 16 to 24-year-olds are aware that too much exposure to the sun is one of the main causes of skin cancer, only around one in 10 actually spend any time in the shade.
The study also suggests there has been a decline in the number of people using sunscreen.
In the last 20 years, the incidence rate of malignant melanoma in 15 to 24-year-olds in the UK has increased by 48%, a spokesman said.
Cancer Research UK spokesman Chris Lunn said: "With all of the unpredictable weather we're experiencing this summer it's key that when the sun does shine, you don't get caught out by sunburn.
"We hear stories of people spending hours in the sun desperate to catch the rays when they do eventually appear, but this comes at a price. As well as the pain that getting sunburnt can cause, it's also a sign that your skin has been irreversibly damaged, which can lead to premature ageing and an increased risk of skin cancer."
The charity made the comments as it launched its Made in the Shade campaign - encouraging youngsters to document their fun in the shade by uploading pictures and videos to the website Tumblr.