People cool off at Cheonggye Stream in central Seoul, Tuesday.
Yonhap Korea's average number of "tropical nights" nationwide hit a record high of 12.1 days since June through Tuesday, the highest average since the country expanded its weather observation network in 1973.
For Seoul, its overnight low temperature recorded 29.1 degrees Celsius Tuesday night, extending its tropical night streak to 14 straight days, according to the Korea Meteorological Administration (KMA).
Read More 43% of greater Seoul area placed under serious heat wave warnings Sweltering heat takes toll on small businesses Seoul's busiest streets sit empty as heat wave emergency grips city A tropical night is defined as a night when the temperature does not drop below 25 degrees.
Seoul nearly reached the threshold for a “super tropical night,” a term the KMA does not officially use but refers to a night when the overnight low is 30 degrees or higher.
