This year's monsoon season started with rains on the southernmost Jeju Island on Saturday.

Monsoon rains began to hit the island on Saturday night, with 100 to 300 millimeters of rain forecast until Tuesday and up to 500 millimeters for mountain areas on the island.

Torrential rains of 40 to 60 millimeters per hour, along with lightning, are forecast for the island until Sunday night, with heavy rain advisories and warnings in place.

According to the Korea Meteorological Administration, as a stationary front is moving northward, monsoon rains are forecast to hit Jeolla, Gyeongsang and Chungcheong Provinces as well on Sunday.

The front will bring showers across the country, including Seoul, on Monday.

Afternoon highs are expected to reach 22 to 33 degrees Celsius on Sunday, with sultry weather forecast for the capital region and Gangwon Province.