Almost all other parts of South Korea, including Busan, Daegu, Daejeon and Gwangju, have already been put under heat wave warnings, according to the KMA.

Heat wave warnings and advisories are issued when daytime highs are projected to exceed 35 C and 33 C, respectively, for at least two days.

The whole country, except for high mountainous regions, has been put under heat waving warnings or advisories, the agency noted.

As of 2 p.m., the daily high temperature soared to 37.4 C in Guri, just east of Seoul, 36.3 C in Gapyeong, 35.4 C in Anseong and 33.9 C in Busan.

KMA and government officials advised that citizens minimize outdoor activities and drink sufficient water to cope with the sweltering heat, as daily high temperatures surged above 35 C in many areas across the country.

They forecast the extremely hot weather, as well as a tropical night phenomenon, will persist nationwide for the time being.

Tropical night is an expression used when the overnight low is 25 C or higher from 6:01 p.m. to 9:00 a.m. the next day.

South Korea's southeastern regions, including Busan, received heavy rain earlier this week due to the landfall of Typhoon Francisco, the eighth typhoon of the season.

Meanwhile, two more powerful typhoons -- Lekima and Krosa, the season's ninth and 10th, respectively -- are also approaching north from the seas near Taiwan and the Philippines, the KMA said, adding that their future routes still remain uncertain. Lekima is projected to move towards China's east coastal areas, while Krosa's course has yet to be known. (Yonhap)