South Korea adds ‘extreme heat emergency’ to first major alert update in 18 years

For decades, the arrival of summer in South Korea was heralded by the rhythmic hum of cicadas and the predictable onset of monsoon season. But as climate change rewrites the country’s seasonal script, the government is bracing for a new reality.On Wednesday, the Korea Meteorological Administration announced a sweeping overhaul of its national weather warning system, the first major restructuring in nearly two decades.The centrepiece of the plan is the introduction of a top-tier “extreme heat emergency” alert – the result of a decade in which scorching afternoons, sleepless “tropical nights” (a meteorological phenomenon where the temperature remains at or above 25 degrees Celsius, or 77 degrees Fahrenheit, between 6.01pm and 9am the following day) and record-breaking torrential downpours have moved from anomalies to the new seasonal baseline.Under the new protocol, which takes effect June 1, the weather agency will move beyond the two-tiered advisory system established in 2008.People walk under cooling mists during a heatwave near Seoul City Hall on August 1, 2025. Photo: EPA“extreme heat emergency” will be triggered when the daily perceived temperature is forecast to hit 38 degrees, or when actual mercury readings are expected to eclipse 39 degrees. It is a threshold designed to signal a shift from discomfort to a legitimate threat to public health and infrastructure.The weather agency’s data paints a stark picture of a peninsula in flux.Over the past five years, the average number of heatwave days and tropical nights has surged nearly threefold compared to the 1970s. The frequency of intense rainfall, with deluges exceeding 50mm (two inches) per hour, has also tripled, often turning urban streets into flash-flood traps.To combat this, the weather agency is also introducing an emergency text alert for catastrophic rainfall approaching 100mm per hour, localised at the township level to prevent the “alert fatigue” of citywide warnings.The climate we knew 20 years ago no longer existsA new tropical night advisory will warn residents when overnight lows are forecast to remain dangerously high in areas already baking under daytime heat.“The climate we knew 20 years ago no longer exists,” the agency said in its briefing.Additionally, by expanding its forecasting zones from 183 to 235 regions, the government hopes that more granular data will allow local officials to deploy disaster responses with the speed that a warming world now demands.Further Reading