South Korea’s worst heat wave in 122 years is moving toward Seoul after pushing temperatures in the country’s south to levels more commonly associated with tropical or desert climates.
Yangsan, a city in southeastern South Korea, recorded 108.5°F, the highest temperature measured since the country began modern weather observations. The intensity of the heat inspired the nickname “Yangfrica,” a combination of Yangsan and Africa.
The comparison captures how unusual this summer has become for a temperate country. Yet the greater concern is no longer the record set in the south. It is the movement of the heat toward the Seoul metropolitan area, where a large share of South Korea’s population is concentrated.
Temperatures across southern South Korea remained above 104°F on Aug. 3. Gwangyang reached 106°F, while parts of Daegu, Uiryeong and Miryang recorded about 105°F. Yangsan cooled slightly to 102°F, suggesting that the most extreme conditions in the south were beginning to ease.
Seoul was moving in the opposite direction. The city’s temperature rose from 94°F at 3 p.m. one day to 97°F at the same time the next day. A monitoring station in the Onsu neighborhood of southwestern Seoul recorded 102°F.
Weather authorities issued the country’s highest extreme heat warning for parts of Seoul and nearby Gyeonggi Province. It was the first time the newly established top level warning had been activated in the capital region.
The shift is being driven by a change in wind direction.
Until recently, winds moving from west to east crossed South Korea’s mountains and descended into the southeast. As the air moved downhill, it was compressed and became warmer, contributing to the record temperature in Yangsan.
The center of the high pressure system has since moved north. Winds around high pressure rotate clockwise, so the change in its position has replaced the westerly flow with easterly winds.
Those winds are now crossing mountains before descending toward Seoul and the surrounding region. The same process that heated southeastern South Korea could therefore raise temperatures in the capital area.
Two large atmospheric systems are reinforcing the heat. The Tibetan high pressure system is positioned over the upper atmosphere, while the North Pacific high pressure system dominates the middle levels. Together, they cover the Korean Peninsula like overlapping blankets and prevent heat from escaping, even at night.
That combination explains why South Korea has become unusually hot even by the standards of an already severe Asian summer. The heat is not being produced by a single hot air mass. It is being trapped from above and intensified locally as winds cross the country’s mountainous terrain.
Seoul could approach 104°F in some districts. The city’s official record is 103°F, set on Aug. 1, 2018.
South Korea’s weather agency has not forecast 102°F at Seoul’s official observation station through the following Thursday. The official city temperature, however, is measured at only one location in the central Jongno district. Other parts of Seoul, including Gangnam, Gangbuk and Nowon, could be hotter.
The movement toward Seoul sharply increases the potential human impact. South Korean authorities recorded 96 heat related patients on Aug. 1, bringing the cumulative total to 1,889. If temperatures in the capital region reach the levels recently seen in the south, far more people could be exposed at once.
The Seoul city government has held an emergency meeting involving officials responsible for disaster response, welfare, public health and firefighting. The city is reviewing whether its existing measures are working in local communities and preparing to expand its response if the heat continues.
Typhoon Dolphin is now the largest uncertainty in the forecast.
The storm could disrupt the stagnant weather pattern and draw cooler air south from the Asian continent. It could also push hot and humid tropical air toward the Korean Peninsula and make conditions worse before any relief arrives.
A similar pattern occurred in 2018, when Seoul set its current temperature record shortly before a typhoon approached.
The path of Dolphin remains uncertain. One possible route would take it into China, while others could bring it north along the Yellow Sea or toward South Korea and Japan. Forecasters expect the storm’s direction to become clearer within several days.
South Korea’s heat wave is therefore entering a more dangerous phase. What began as record temperatures in the south is now moving toward the country’s most densely populated region, where the same weather could produce a much larger human toll.
