South Korea expects nationwide heavy rain tonight with some areas potentially receiving up to 120 mm of precipitation [2].

This weather pattern is significant because it follows a period of extreme heat and threatens to trigger flooding in the capital region and coastal areas. The sudden influx of heavy rain creates immediate risks for urban infrastructure and maritime safety.

The precipitation is attributed to tropical moisture left behind by Typhoon BOBI [4]. According to the meteorological agency, rain is expected to begin during the day in the capital area, Chungnam, and Honam, before spreading to the Yeongnam region by tonight [3].

Specific areas of concern include northern Gyeonggi, the capital area, northern Gangwon, and western sea areas such as Baengnyeongdo [2]. While some reports from the meteorological agency forecast between 30 and 100 mm for the capital area [1], other reports indicate a maximum of 120 mm could fall overnight [2].

High temperatures and humidity continue to affect the region. At 9 p.m., the temperature in Sangam-dong was recorded at 28°C, with a heat index making it feel like 31.2°C [2].

"Today, heavy monsoon rain has been forecast nationwide, and it appears that a lot of rain, up to 120 mm, will pour down overnight," Park Seok-won said [2].

Local officials are monitoring the situation as the country prepares for the possibility of a return to extreme heat once the rain subsides [2].

“Up to 120 mm of rain is expected across the peninsula.”

The interaction between lingering typhoon moisture and the existing monsoon season creates a volatile weather cycle. The transition from extreme heat to heavy rainfall and back again increases the risk of flash flooding and heat-related illnesses, putting pressure on South Korea's disaster management systems in highly populated urban centers.