South Korea is enduring a severe and unprecedented heat wave, with Seoul placed under its highest-level heat alert for the first time on Tuesday as daytime temperatures threatened to reach 38°C. The Korea Meteorological Administration (KMA) issued what it calls a "serious heat wave warning" across all districts of the capital, completing coverage of the city after southern areas were placed under the alert the previous day. The warning threshold requires that the highest perceived temperature reach 38°C or above, or that the maximum daily temperature hit 39°C or higher, in areas that have already recorded perceived temperatures of 35°C or more for at least two consecutive days.

The extreme conditions are being felt far beyond Seoul. Large parts of Gyeonggi Province — the densely populated region surrounding the capital — as well as cities in the southwestern Jeolla provinces, including Jeonju and Yeosu, have also come under the highest-level alert. In one of the most striking records of the current crisis, the southeastern inland city of Yangsan recorded a temperature of 42.5°C on Sunday, the highest figure measured in 122 years of weather observations in South Korea.

The human toll is mounting. At least 16 people have died nationwide from heat-related causes, according to President Lee Jae Myung, who addressed the crisis at a cabinet meeting on Tuesday. In Seoul alone, 185 heat-related illness cases have been recorded since May 15, including two deaths, with 18 new cases reported in the capital on Monday alone. The interior ministry sent emergency text messages to citizens urging them to stay indoors, drink plenty of water, and check on vulnerable family members.

Authorities have launched a broad emergency response. Seoul's city government has designated approximately 4,000 locations — including community centres, senior citizen facilities, and welfare centres — as cooling shelters, while also watering roads to reduce urban heat and targeting outreach at residents living in cramped or poorly ventilated housing. President Lee called on officials to inspect power infrastructure as demand for air conditioning surges, warning that such extreme weather events are becoming increasingly frequent. "We need to make efforts for a fundamental overhaul of the national crisis system, since this extreme weather is becoming normal," he said.

The serious heat wave warning itself is a new addition to South Korea's advisory system, having only been introduced on June 1 this year — making Tuesday's city-wide alert for Seoul a significant first test of the upgraded framework. The crisis underscores the growing challenge facing dense urban centres in East Asia as record temperatures become harder to dismiss as anomalies.