Korea's summers are getting longer and hotter, data shows

Korea's summers are becoming longer and more intense as heat waves arrive earlier, persist longer, with tropical nights growing increasingly common.

A new analysis released by the Korea Meteorological Administration (KMA), Friday, compared heat wave and tropical night patterns from 2016 to 2025 with those recorded from 1973 to 1982.

It found that heat waves now begin 10 to 30 days earlier nationwide and end about 10 days later than five decades ago.

A heat wave is defined as a day with a high of at least 33 degrees Celsius, while a tropical night refers to one in which temperatures stay above 25 degrees overnight.

In Gangneung and parts of the Yeongnam region, including Daegu, Hapcheon, Miryang, Yeongdeok and Pohang, where heat waves tend to arrive earlier than in other parts of the country, the onset of heat waves has shifted to early June over the past decade, more than 10 days earlier than during the 1973 to 1982 period, when they typically began in mid- to late June.

A similar shift has been seen across inland central regions, including Seoul, Icheon, Chuncheon and Cheongju, where he ...