Heavy rain advisories are in place for Seoul, Gyeonggi and South Chungcheong Provinces.
More than 30 millimeters of rain will fall per hour in areas including Seoul, Gyeonggi Province, and the western Gangwon Province until Tuesday afternoon due to a monsoonal front coming in from the western sea.
The front will move on to Chungcheong Province and southern regions of the peninsula on Wednesday.
Expected precipitation until Wednesday stands at 80 to 150 millimeters in the southern regions, more than 200 millimeters in Jeolla Province and the Mount Jiri area, and between 30 and 120 millimeters in central regions including Seoul.
The rain will be accompanied by thunder and lightning in some areas. Strong winds are also expected.
The rain in the central regions will continue until early Wednesday morning, but will last until Saturday in the southern regions. Heavy rain will hit the nation again on Sunday.