South Korea expects nationwide extreme heat on Monday, July 13, with daytime temperatures reaching up to 36 °C [1].

This prolonged heat wave is significant because the high temperatures are persisting into the night, preventing the environment from cooling down and increasing the risk of heat-related illness.

Weather caster Lee Hye-min said the extreme heat will continue tomorrow [2]. On Sunday, temperatures in Yangju reached 36 °C [2], while Seoul recorded a maximum temperature of 35 °C [2]. Lee said today felt like being inside a steamer due to the high humidity [2].

The heat is not limited to the daytime. Nighttime temperatures are expected to remain at or above 25 °C in many areas [2]. These conditions have prompted a tropical-night warning across the country, a phenomenon where the lack of nocturnal cooling exacerbates physical stress on the population.

Forecasts for Monday morning indicate high starting temperatures across major cities. Seoul and Gangneung are expected to start at 26 °C, while Gwangju and Pohang are projected to be 27 °C [2].

An anchor for YTN said that a nationwide "steamer-like heat" is expected to persist through Monday [2]. Residents in affected areas, including Seoul and Gwangju, are advised to take precautions against the intensifying humidity and heat.

“Today was hot and humid, as if we had entered a steamer.”

The convergence of high daytime peaks and tropical nights creates a compounding effect on public health. When nighttime temperatures do not drop below 25 °C, the human body cannot recover from daytime heat stress, which typically leads to higher rates of insomnia, exhaustion, and increased energy demand for cooling systems across South Korean urban centers.