South Korea has expanded its critical heat warnings to include cities such as Changwon and Jinju as extreme temperatures grip the nation [1].

The expansion of these alerts signals a dangerous shift in weather patterns, as the combination of high heat and humidity increases the risk of heat-related illnesses across the peninsula.

Officials said the current conditions are the result of the monsoon season ending and a high-pressure system, often described as a heat dome, covering the region [1, 3]. This atmospheric phenomenon has trapped hot, humid air over the land, creating what local reporters described as a "steamer" effect.

Temperature readings on Monday showed significant spikes in the southern regions. In Dong-myeon, Yangsan, the temperature reached 37.7°C [1], with some reports noting it nearly hit 38°C [1]. Meanwhile, Geumjeong District in Busan recorded a temperature of 35.7°C [1].

Even in the capital, the heat remains oppressive. Seoul recorded a perceived temperature, or heat index, of 34°C [1, 2]. The persistent high humidity makes these temperatures feel more severe than the actual thermometer reading, complicating cooling efforts for urban residents.

This is not the first time the country has faced such extremes this month. Earlier on July 13, the first-ever critical heat warnings were issued for Pohang and Gyeongsan in North Gyeongsang Province [3]. The current expansion of these alerts to more cities indicates that the heatwave is intensifying and spreading.

"Essentially, the monsoon has ended, and the steamer heat is rampant," a YTN news anchor said [1]. A reporter for the same network said that the country is now "trapped" in this hot and humid environment [1].

Local authorities continue to monitor the heat dome's movement, as the lack of rainfall and the presence of the high-pressure system prevent the temperature from dropping significantly during the night.

“Essentially, the monsoon has ended, and the steamer heat is rampant.”

The transition from the monsoon season to a heat dome indicates a period of prolonged thermal stress for South Korea. Because the 'critical heat warning' is a high-level alert, the expansion to multiple cities suggests that the current weather event is exceeding typical seasonal norms, potentially straining the national energy grid and public health infrastructure.