Heavy rain, accompanied by gusts of wind, thunder and lightning, was set to spread nationwide through Friday due to the northward movement of the monsoon front.

As of 3 p.m. Thursday, heavy rain advisories have been issued in the Seoul metropolitan area, inland Gangwon, Chungcheong, North Gyeongsang and Jeolla provinces.

The Korea Meteorological Administration forecast very heavy rain of 30 to 60 millimeters per hour nationwide by Friday, calling for extra caution as the ground has been already weakened by the downpour in the first half of the week.

Rain is expected to continue through Thursday night in the central region of the peninsula, while the southern part of the country and Jeju Island will receive more rain until Friday afternoon.

Meanwhile, the first death caused by the heavy rain this year came as a floodgate manager in Hampyeong-gun, South Jeolla Province, who went missing was found dead.

The 67-year-old surnamed Oh was found dead near the pump station pier in Hampyeong County at around 10:37 a.m. Thursday, according to fire authorities.

Oh went out with her husband near the river to check the floodgates when torrential rains caused the river to swell on Tuesday evening. While her husband had gone to grab a flashlight, Oh is believed to have been swept away by the current while removing floating debris around the floodgates.