On Sunday, August 2, 2026, the city of Yangsan in south-eastern South Korea reached 42.5°C. That is the highest temperature ever recorded in the country since modern weather tracking began in 1904, according to the Korea Meteorological Administration (KMA) (The Japan Times).

It was the fifth day in a row that Yangsan's temperature went above 40°C. More than 20 places across the country were under emergency heatwave alerts that same day. This is a new type of alert introduced in 2026. It triggers when areas already in a heatwave are expected to feel like 38°C or hit an actual temperature of 39°C (The Guardian). "Feels like" temperature means how hot it actually feels to your body when humidity and other factors are included.

The KMA told the public to "immediately stop all outdoor activities" and warned that being indoors without air conditioning is dangerous. The warning shows how serious the situation is — both the felt and actual temperatures have stayed above emergency levels for several days in a row.

The heat is disrupting daily life. South Korea's professional baseball league canceled a game in the city of Changwon after temperatures there reached 39.5°C. It was the second game in a row called off in that city. Canceling professional sports games because of heat is not normal in South Korea, and the back-to-back cancellations show that local officials and the league considered the conditions unsafe to play in.

The background numbers tell a clear story. KMA data show that South Korea now averages about 19 heatwave days per year, where a heatwave day means the temperature reaches at least 33°C. That is more than double what it was five years ago. A typical year now has about three weeks of these hot days, compared to a much lower number in the past. This trend lines up with broader warming patterns across the region and the world, though the causes behind any single extreme event involve many factors.

One of those factors is El Niño. El Niño is a natural climate event that warms the surface of the Pacific Ocean every two to seven years. It returned in 2026 and has been adding to extreme weather around the world (The Guardian). You can think of El Niño as a temporary burst of extra heat on top of a planet that is already warming from human activity. Scientists have studied this interaction for years. El Niño tends to push temperatures even higher than they already would be. For the Korean Peninsula, that can mean hotter summer peaks and longer heatwaves.

The broader context here is that South Korea's systems for responding to dangerous heat are being tested by conditions unlike anything they have dealt with before. The fact that the government created a new emergency alert category in 2026 suggests the old warning levels were no longer enough for today's temperatures. When the KMA tells people to stop all outdoor activity and calls non-air-conditioned indoor spaces hazardous, it is responding to a situation that the country's 122-year weather record has never produced.

The doubling of heatwave days over five years also has effects beyond health warnings. Long stretches of extreme heat put pressure on power grids, damage crops, make outdoor work harder and more dangerous, and raise the risk of death for elderly and other vulnerable people. South Korea's power grid operators and city governments have been making adjustments, but the temperature data suggests that these changes are not keeping up with how fast the heat is increasing.

Whether this event turns out to be unusual or becomes the new normal will depend partly on how El Niño develops through the rest of 2026 and into 2027. What is already clear is that South Korean authorities now have to plan for conditions that have shifted. Yangsan's 42.5°C reading did not happen by itself. It was the peak of a multi-day heatwave in a year that has already put serious strain on the country's systems.