A monitor at the Korea Meteorological Administration in Dongjak District, southern Seoul, displays the current temperature of 39 degrees Celsius (104 degrees Fahrenheit) in Yangsan, South Gyeongsang, on July 28, as the heat wave continues.YONHAP
Southern Korea is enduring daytime highs approaching 40 degrees Celsius (104 degrees Fahrenheit) while the greater Seoul area faces intense tropical nights as the monsoon season ends and the scorching heat begins.
Daytime high in Yangsan, South Gyeongsang, reached 39 degrees on Tuesday, according to the Korea Meteorological Administration (KMA). The city has seen daytime temperatures exceed 39 degrees on three of the past four consecutive days, making it the hottest spot in the country recently.
The KMA issued the highest heat advisory for Yangsan, as well as parts of South Gyeongsang, including the Uiryeong and Changnyeong counties. Daegu, a famously hot city located inside North Gyeongsang, has also seen nine consecutive days of daily highs of 33 degrees or above, through Tuesday.
The greater Seoul area is experiencing intense tropical nights. Seoul has recorded seven consecutive tropical nights from last Wednesday through Tuesday. A tropical night is defined as one in which the overnight low does not fall below 25 degrees. According to the KMA, the nationwide average number of tropical nights this year from June 1 to Monday stood at 7.8 days, which is the highest figure on record since nationwide weather observations began in 1973.
The administration's analysis of daily highs and lows nationwide on Monday found that extreme daytime highs near 40 degrees were concentrated in the North and South Gyeongsang regions. At night, however, the greater Seoul area recorded the highest temperatures in the country.
The same pattern held for perceived temperature. The "feels like" temperature was highest in Yeongnam during the day and in the greater Seoul area at night. In some parts of Seoul, high humidity kept the perceived nighttime temperature from dropping below 30 degrees at all.
Heat haze rises from a road near Suseong Lake in Daegu's Suseong District on the morning of July 27 as the heat wave continues.NEWS1
Forecasters attribute the shifting day-night heat map largely to a band of clouds hanging over central Korea. The clouds blocked sunlight during the day but trapped heat at night, preventing it from escaping and driving the unusually intense nighttime warmth.
"In the southern region, three factors — persistent southerly winds, strong sunlight and topographic effects — pushed daytime temperatures higher," said Woo Jin-gyu, a forecaster at the KMA. "In the greater Seoul area, on the other hand, the clouds acted like a blanket, trapping heat and preventing temperatures from dropping as much at night."
The urban heat island effect, in which cities retain heat overnight, is also cited as a factor behind the rise in tropical nights in the greater Seoul area. Comparing average temperatures in urban and nonurban areas over the past 52 years, from 1973 to 2024, the KMA found little difference in daytime highs, but nighttime lows were 1.3 degrees higher in cities than in nonurban areas. Tropical nights also occurred 2.2 times more often in urban areas.
As the North Pacific High is set to expand further later this week, the area affected by extreme heat is expected to spread from the Gyeongsang region to the rest of the country. Weather experts say the heat, affecting both day and night, could persist through September and urged the public to prepare for the effects of heat waves and tropical nights.
"As the North Pacific High and the Tibetan High blanket the Korean Peninsula like a quilt, the resulting heat dome effect will make it difficult for heat that builds up during the day to escape at night," said Ban Ki-seong, the CEO of K-Climate. "The risk of heat-related illness could rise sharply, so it's important to follow the three basic rules: Drink water, seek shade and rest."
This article was originally written in Korean and translated by a bilingual reporter with the help of generative AI tools. It was then edited by a native English-speaking editor. All AI-assisted translations are reviewed and refined by our newsroom.
