A "major heat wave alert" was issued for the first time in Gyeongsan and Pohang in North Gyeongsang Province at 10 a.m. on the 12th. It was the first issuance since the system was newly established on the 1st of last month. The Korea Meteorological Administration (KMA) said the heat had reached a level at which even healthy people are highly likely to suffer heat-related illnesses, and urged people to stop outdoor activities immediately and move to shade or cooling shelters to rest.
The major heat wave alert is the highest-level heat advisory, one step above the existing heat wave warning. It is issued when the daily maximum perceived temperature is expected to reach 38 degrees Celsius or higher, or the daily maximum temperature 39 degrees or higher, for at least one day in areas where the daily maximum perceived temperature has remained at 35 degrees or higher for two or more days.
The KMA introduced the major heat wave alert last month to respond to "extreme heat" for which a heat wave warning alone is insufficient to convey the level of danger. As a result, the heat advisory system was overhauled for the first time in 18 years.
The alert came amid an unusual heat wave blanketing the entire country. With the North Pacific high-pressure system and the Tibetan high-pressure system doubly covering Korea, the southern part of North Gyeongsang Province has seen temperatures soar far higher than other regions, compounded by a "foehn phenomenon" in which hot southerly winds heat up further as they cross over mountains.
In Gyeongsan, the temperature rose to 37.9 degrees at 3:08 p.m. the previous day based on the automated weather observation equipment in Jungbang-dong, while Hayang-eup recorded 39.9 degrees, approaching 40 degrees. In Pohang, the highest temperature at the representative point of Songdo-dong in Nam-gu was 34.0 degrees, but Gigye-myeon soared to 37.2 degrees at 3:04 p.m. The KMA forecast that the highest temperatures in Hayang-eup and Gigye-myeon would rise to 39 degrees on this day.
Gyeongsan is also cited as the region most likely to see the major heat wave alert issued most frequently. According to the KMA's analysis of temperature data over the 10 years from 2016 to last year, applying the current criteria, the major heat wave alert would have been issued in Gyeongsan an average of 3.1 days per year. This is the highest level among all advisory zones nationwide.
Gyeongsan's heat intensity stands out even more considering that 53% of all advisory zones did not experience heat meeting the major heat wave alert criteria even once during the same period. Following Gyeongsan, the estimated number of issuance days was highest in Yeoju, Gyeonggi Province (2.5 days), followed by Anseong (2.2 days), Daegu (1.6 days), and Yongin, Gyeonggi Province (1.6 days).
Even in 2018, dubbed "the worst heat wave of the 21st century," an analysis showed that if the current criteria had been applied, the major heat wave alert would have remained in effect in Gyeongsan for eight consecutive days. This is the longest sustained case based on advisory zones, along with Yongin, Gyeonggi Province in 2024.
Heat at the level of a major heat wave alert is known to make even healthy people highly likely to suffer heat-related illnesses. The KMA emphasized that when a major alert is issued, people should immediately stop outdoor activities, move to cooling shelters or shade, drink plenty of fluids, and rest. It also urged people to regularly check on the well-being of neighbors, such as elderly people living alone or with family.
An analysis by the Korea Disease Control and Prevention Agency of the KMA's temperature observation data from 2016 to 2024 and death cause data from the National Data Portal also found that when the major heat wave alert criteria are met, with a daily maximum perceived temperature of 38 degrees or higher or a maximum temperature of 39 degrees or higher, the relative risk of death is 1.16 times higher than normal.
