Heavy rains battered southern provinces overnight, leaving one person missing, and dozens of homes without power after a lightning strike, while the downpour is likely to continue in the region throughout Wednesday morning.

Up to 274 millimeters of rain fell in South Jeolla and South Gyeongsang provinces between Tuesday night and Wednesday morning, prompting the anti-disaster office under the interior ministry to upgrade the heavy rain advisory to "alert" from "caution."

As of 7 a.m. rain was still pouring at a rate of 10 to 30 mm per hour in the southwestern city of Gwangju, South and North Jeolla provinces, and 5 to 10 mm per hour in South Gyeongsang Province, according to the Korea Meteorological Administration.

The damage was concentrated in Gwangju and its surrounding South Jeolla Province.

A woman in her 60s went missing in a rural village in the county of Hampyeong, where 71.5 mm per hour of rain swept the region on Tuesday night, after she left home to open a floodgate. A search for the missing person is under way.

Twenty-one people were evacuated from their homes in Gwangju, South Jeolla Province and South Gyeongsang Province after trees fell on their houses or due to fears of flooding.

Some 30 households suffered a power outage due to a lightning strike in Gwangju.

Traffic was blocked off from 15 roads, two underpasses, nine riverside parking lots and 35 bridges, while 10 national parks and 299 hiking trails were off limits, according to the Central Disaster and Safety Countermeasure Headquarters.

The volume of precipitation recorded in an hour in June peaked this year, beating its previous records in many regions, including 54.1 mm in Gwangju, and 74.5 mm in Namhae county in South Gyeongsang Province on Tuesday, and 49.3 mm in Buan county in North Jeolla Province on Wednesday.

The monsoon rain is expected to come to a lull due to the influence of high atmospheric pressure nationwide, but the greater Seoul region, the western region in Gangwon Province, and Chungcheong Province will see showers accompanied by strong wind, lightning and thunder until the afternoon. It will travel to affect the inland areas of South and North Jeolla provinces and North and South Gyeongsang provinces in the afternoon.

The state weather agency also warned against possible ice pellets, a type of hail, in the region. (Yonhap)