Weather authorities issued heat wave advisories nationwide on Tuesday in response to a heat wave that has been gripping South Korea, with the capital city experiencing its second straight “tropical night” this week.

The so-called tropical night phenomenon is defined by nighttime lows staying above 25 C, with nighttime being from 6 p.m. to 9 a.m.

It often happens when monsoon season ends, which falls in July in general for the country.

Overnight lows across the nation soared well above the threshold on Monday, with the eastern coastal city of Gangneung recording the highest temperature at 28.7 C followed by the southern city of Pohang at 27.1 C. The temperature overnight in Seoul also reached 25.8 C to mark its second consecutive tropical night, according to the Korea Meteorological Administration.

The scorching heat led the weather authorities to issue the country’s first heat wave warnings in the southeastern city of Daegu and its surrounding areas in North Gyeongsang Province, set to take effect from 11 a.m. The daytime highs in the region are forecast to soar above 35 C, according to the KMA.

The agency also extended the heat wave advisories from the southern regions to the central part of the country including Seoul and the surrounding Gyeonggi areas starting at 11 a.m., with the daytime high in Seoul being expected to climb to 32 C.

Heat wave advisories are issued when the mercury goes over 33 C for at least two days, and heat wave warnings are issued when it soars up to 35 C for at least two consecutive days.

The heat wave on the Korean Peninsula is forecast to be unabated until at least the end of July due to the influence of a hot and humid North Pacific high temperature system, the weather agency said. (Yonhap News)