Officials reported 166 newly confirmed cases as of Saturday night.
That was the highest since March 11, when South Korea reported 242 amid an outbreak in the southeastern city of Daegu and nearby towns.
With 103 new cases reported Friday, this is the first time since late March that the daily increase surpassed 100 two days in a row.
Officials say all but 11 of the new cases were local transmissions, and most were in the Seoul area.
In another development, Reuters reported that South Korea's President Moon Jae-in also had said on Saturday (Aug 15) that said his government was always ready to talk with Japan over historic disputes,
Moon's comments were made in a speech celebrating 75 years of liberation from Japan's 1910-1945 colonisation of the peninsula.
The Asian neighbours are at loggerheads over a 2018 decision by South Korea's Supreme Court that ordered a Japanese steelmaker to pay compensation for forced labour during World War II.