Authorities have warned people in affected areas to immediately cease any outdoor activities.
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In the southeastern city of Yangsan, the temperature reached 42.5 degrees Celsius at 13:26 local time (7:26 Lithuanian time), reported the Korea Meteorological Administration (KMA) on its website.
Yangsan is the epicenter of the ongoing heatwave, where the temperature exceeded 40 degrees for the fifth consecutive day on Sunday. In many other cities, including Daegu and Busan, temperatures are approaching 40 degrees.
People flocked to air-conditioned shopping malls or cafes to escape the scorching heat, observed a journalist from the news agency AFP.
More than 20 locations were issued extreme heatwave warnings on Sunday – a new warning category introduced this year to better respond to rising temperatures.
An extreme warning is issued when the perceived temperature in heatwave-affected areas is forecast to reach 38 degrees or when the actual daytime temperature will be 39 degrees.
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When issuing the heat warning, the meteorological agency urged people to “immediately stop any outdoor activities” and added that “indoor spaces without air conditioning are dangerous.”
“Immediately go to a cool place, such as a special cooling center or shade, and drink plenty of fluids while resting,” it advised.
KMA data shows that the average annual number of heatwave days in the country has more than doubled over the past five years – up to 19, compared to eight in the 1970s.
A heatwave day is defined as a day when the highest temperature reaches at least 33 degrees.
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