South Korea experiences record-breaking streak of tropical nights

Seoul, Busan and many other parts of South Korea are currently experiencing a rare and unprecedented heat wave, shattering records for consecutive tropical nights.

A tropical night refers to overnight temperatures remaining at or above 25 degrees Celsius from 6:01 p.m. to 9 a.m. the following day. 

As of Sunday, the capital city, Seoul, had sweltered through 28 tropical nights since July 21, according to the Korea Meteorological Administration (KMA). 

This extraordinary streak is the longest stretch of tropical nights since modern meteorological observations began in Seoul in 1907. The previous record was 26 nights, set in 2018. 

Busan has endured a record-breaking 24 consecutive tropical nights since July 25, surpassing the previous record of 21 days set in both 1994 and 2018.

Traditionally, tropical nights occur when daytime heat lingers into the evening. This year, a persistent warm southerly wind has exacerbated the effect, leading to unusually high overnight temperatures since last month.

"The cold air is not coming down from the north," Youn Ki-han, director at Seoul's Meteorology Forecast Division, said. 

"Usually around this time, the temperature drops in the morning and evening ... but currently, we aren't seeing any signs of that yet," said Youn.

Despite heavy rain predicted for Monday, temperatures are expected to rebound quickly, maintaining the conditions for tropical nights.

According to the International Institute for Environment and Development (IIED), the number of days with temperatures reaching 35 degrees Celsius in the world's largest capital cities has surged by 52 percent over the past 30 years. 

In 2018 alone, Seoul experienced 21 days with temperatures over 35 degrees Celsius, more than the previous 10 years combined.

"In just one generation, there's been an alarming increase," said Tucker Landesman, PhD, a senior researcher at IIED.

The KMA announced plans to release its first-ever white paper on heat waves by the end of the year. While the agency has previously published white papers on monsoon seasons, typhoons and El Niño, this will be the first dedicated to heat waves. 

The decision comes in response to the increasingly severe heat waves in recent years, including this year's extreme conditions, which the KMA sees as having reached a disaster level.

(With input from AFP)