Hong Kong has been issued a “very hot weather” warning by the Observatory on summer solstice day. The warm weather is expected to continue through the weekend. A weather expert has cautioned that heatwaves will intensify in the city due to climate change.
The warning, the second this year, was raised with a prolonged heat alert at 6.45am.
“Under the influence of the subtropical ridge, the weather is generally fine over the coast of Guangdong,” the forecaster said.
“The maximum temperature will be around 33 degrees Celsius [91.4 Fahrenheit] in urban areas and a couple of degrees higher in the New Territories.
“Under the influence of prolonged heat, members of the public should stay on alert to prevent heatstroke or other discomfort related to very hot weather and pay due attention to health conditions.”
Temperatures may rise to 34 degrees on Saturday and Sunday, according to the forecast.
The city marked its hottest day of the year amid widespread heatwaves in the United States, Mexico and Greece, among others.
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Leung Wing-mo, former assistant director of the Observatory, said climate change played a “vital role” in the city’s very hot days and growing number of heatwaves.
He added that every 0.1-degree rise in temperature would lead to a “big increase” in the number of heatwaves, citing a recent report by the Intergovernmental Panel on Climate Change.
“Without exception, heatwaves are the extreme weather that is strongly associated with global warming,” he said.
Between 2010 and 2019, Hong Kong logged about 27 very hot days on average a year, according to calculations by the Post. Over the past three years, that number has climbed to over 50.
According to the Observatory’s latest climate projections, Hong Kong could see as many as 80 very hot days by mid-century under the highest greenhouse gas emission scenario.
Leung added that the summer solstice also played a part in bringing hot temperatures to the city.
The summer solstice is when the sun climbs above the Tropic of Cancer, which is situated on a similar latitude as that of Hong Kong, according to Leung.
“It means that the sun is almost directly overhead of Hong Kong, so the solar intensity is the strongest this time of the year,” he said, adding the normally wet and cloudy weather in June would usually dampen its effects.
But he also said there might be fewer very hot days this year overall, compared with 2023 given that the world was transitioning from an El Nino to La nina.
“With the effect of La nina, seawater in the eastern equatorial Pacific is cooling, so I don’t expect as many very hot weather days as last year,” he said.
The Centre for Health Protection also called on the public to take extra care of elderly people, pregnant women and children, and watch out for any heatstroke symptoms.
“The public should carry and drink plenty of water to prevent dehydration while engaging in outdoor activities,” a spokesman for the centre said.
“Those engaged in strenuous outdoor activities should avoid beverages containing caffeine, such as coffee and tea, as well as alcohol, as they speed up water loss through the urinary system.”
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An amber heat stress at work warning was also issued at 8.50am by the Labour Department. It indicates high heat stress in certain working environments.
Outdoor workers are reminded to take necessary precautions against hot weather under the guidelines of the department.
Appropriate rest breaks should be arranged every hour, as far as reasonably practicable, to reduce heatstroke risks among employees, a department spokesman said.
People showing any symptoms of heat-related illnesses, such as headache, dizziness, thirst and nausea, should rest in a cool and shady place, drink water and inform employers and supervisors to take appropriate action immediately, he added.
The last very hot warning was issued on June 13 and lasted for more than 3½ hours.