"Extreme heat on a scale we have never experienced is continuing day after day. Heatwave conditions once seen only in foreign news reports have now become our reality," President Lee Jae-myung told a heatwave response meeting on Thursday.
Lee ordered ministries and local governments to mobilise all available personnel and resources until the heatwave eases, stressing protection of lives and safety, stronger safeguards for vulnerable residents and stricter enforcement of rest breaks for outdoor workers during the hottest hours.
The forecast temperature would bring Seoul close to its record high of 39.6C, set in August 2018, during the country's last historic heatwave.
The warning came as Seoul endured another stifling night before what forecasters say could be one of the hottest days in the city's modern history.
Temperatures in some neighbourhoods barely slipped below 30C overnight, according to the Korea Meteorological Administration (KMA), while media showed crowds seeking refuge in streams, department stores and other air-conditioned spaces.
The Korea Baseball Organisation cancelled all 10 games scheduled for Wednesday and Thursday after some spectators fainted in the heat, media reported, including one fan who collapsed during a game in Incheon.
Meteorologists say Typhoon Dolphin, despite posing no direct threat to South Korea, might be contributing to the scorching conditions.
The KMA said Dolphin has helped strengthen easterly winds that cross the Korean Peninsula's mountainous spine and descend over western regions as hot, dry air, intensifying heat in Seoul and elsewhere.
9°C