Heavy rain is forecast to sweep across South Korea beginning Sunday, with the Korea Meteorological Administration (KMA) warning of widespread downpours and potential weather-related hazards.

Clouds are expected to gradually blanket the country throughout the day, bringing rain to most regions by nightfall.

Precipitation will begin in Jeju and the Jeolla Provinces before expanding to South Chungcheong and South Gyeongsang Provinces in the afternoon, eventually reaching the rest of the nation by nighttime.

According to the KMA, southern coastal areas, Mount Jiri, and mountainous regions of Jeju Island could receive up to 250 millimeters of rain through Tuesday.

Gyeonggi, South Chungcheong, Jeolla and South Gyeongsang Provinces, as well as Jeju's coastal areas, are expected to see more than 150 millimeters, while the capital region and other inland areas may receive 50 to 100 millimeters.

Authorities are urging caution, as some areas may experience torrential rainfall of 50 to 80 millimeters per hour, accompanied by thunder, lightning and strong winds between Sunday afternoon and Monday morning.

Temperatures are expected to dip slightly, with daytime highs ranging from 30 to 34 degrees Celsius, two to five degrees lower than Saturday's peak.