The tropical night phenomenon continued in Seoul and other major cities across the country, the state weather agency said Monday.

The minimum temperature between Sunday night and Monday morning was 27.5 C in Seoul, 27.1 C in Incheon, 25.6 C in Busan and 26.8 C on Jeju Island, according to the Korea Meteorological Administration (KMA).

A tropical night occurs when the temperature does not fall under 25 C during the nighttime.

The country has been in the grip of an intense heat wave for about two weeks.

Heat wave alerts have been issued for most of the country Monday, with daytime highs forecast to reach 36 C for Seoul, 34 C for Incheon, 33 C for Daegu and 37 C for Chuncheon.

Some areas in Seoul and the nearby cities of Incheon, Goyang and Gimpo suffered from power outages as the searing weather increased electricity demand, local offices of the Korea Electric Power Corp. (KEPCO) said.

A 750-household apartment complex in Incheon, 40 kilometers west of Seoul, was hit by a blackout between 8:10 p.m. and 5 a.m.

Electricity also was cut at a 670-unit apartment complex in Goyang, northwest of Seoul, for more than seven hours, while the mercury remained over 26.6 C.

The KMA said the number of extreme heat days, or days with maximum temperatures of 33 C or higher, in Seoul this year is expected to exceed the normal level.

Seoul experienced nine extreme heat days this year until Sunday, already surpassing the average annual extreme heat days of 8.7 from 1991 to 2020.

The number of tropical nights in Seoul during the same period came to 11, slightly fewer than the annual average of 12.5 days.

The weather agency forecast the heat wave will continue until Aug. 5, with maximum temperatures expected to hover around 35 C across the country. (Yonhap)