The entire country is suffering from scorching heat day and night due to the movement of a hot and humid air mass from the tropics to the Korean Peninsula. According to the Korea Meteorological Administration, the high temperature in most of the major cities in Korea on Monday topped 30 degrees Celsius. The high in Daegu was 36 degrees, in Gwangju 33.2 degrees, in Daejeon 31.2 degrees, and in Gangneung 32.3 degrees. The difference between the daytime high and nighttime low was just 2.7 degrees, 4 degrees lower than the previous year.

A hot and humid North Pacific anticyclone is a major reason behind the continued heat wave. As the rainy season nears its end, the humidity of the anticyclone stretched its influence to the Korean Peninsula. "Vapor condensed in the North Pacific anticyclone narrows down the temperature difference because it stays in the air and holds the heat," said Prof. Ho Chang-hoi of the School of Earth and Environmental Sciences of Seoul National University.

Since a special heat wave warning was first issued in the east coast on Saturday, warnings were issued in North Chungcheong Province and 46 other cities and counties nationwide on Monday. A heat caution was issued in five regions including Gimcheon in North Gyeongsang Province and Hamyang County in South Gyeongsang Province.

While the whole country is steaming during the day, the number of cities experiencing "tropical nights," when the nocturnal low stays above 25 degrees, has increased. Starting with Gangneung on Friday, the tropical night expanded to Gangneung and Daegu on Saturday, six regions on Sunday, and 17 regions on Monday.

The KMA predicted Monday that the heat wave will continue in all parts of the country except for Seoul and some parts of Gyeonggi Province until Thursday, with daytime highs above 30 degrees. Temperatures will drop temporarily on Friday, as a rain front sinks in from the north.

(englishnews@chosun.com )