South Korea is experiencing a shift in summer monsoon patterns toward shorter but more intense rainfall events that increase the risk of flooding [1].

This change in precipitation behavior suggests that traditional drainage and flood prevention systems may be inadequate for the new reality of extreme, concentrated downpours. As the atmosphere holds more moisture due to rising temperatures, the nature of the rainy season is evolving from steady precipitation to erratic, high-volume bursts.

Last year, the country saw extreme rainfall exceeding 100 mm per hour [1]. These intense events occurred in 15 different locations, including Gunsan, Seosan, and Sancheong [1]. This trend marks a significant departure from historical norms recorded by the Korea Meteorological Administration over the last 113 years [1].

Son Seok-woo, a professor in the Department of Earth-Environmental Science at Seoul National University, said that while total precipitation was slightly below average last year, the number of rainy days was record-low. He said that much more powerful concentrated heavy rains were created over shorter periods than usual [1].

Climate change is the primary driver of this phenomenon. Rising global temperatures increase the amount of moisture the atmosphere can hold, which leads to fewer rainy days overall, but more violent storms when precipitation does occur [1].

With the monsoon season typically beginning in late June, officials and residents are preparing for a period where the volume of rain is less predictable but the intensity is higher [1]. The pattern of "pouring" rain rather than steady rainfall creates immediate pressure on urban infrastructure and rural slopes, often leading to repeated flooding in the same areas [1].

“Extreme rainfall exceeding 100 mm per hour occurred in 15 different locations.”

The transition from consistent seasonal rain to 'extreme bursts' indicates that South Korea's climate is mirroring global trends of intensification. This shift means that historical weather data is becoming less reliable for urban planning, requiring a move toward 'sponge city' infrastructure and more agile emergency response systems to handle flash floods that exceed 100 mm per hour.