"It is worrisome that the stronger-than-expected typhoon could inflict additional harm on our country, including Pohang and Gyeongju that were damaged by Typhoon Hinnamnor," Yoon was quoted as saying by the news agency.
The South Korean president also urged disaster management authorities to maintain thorough readiness for the storm and to "respond seriously to Nanmadol to an extent that could be seen as excessive," according to the news agency.
The previous Hinnamnor typhoon, that swept thought the country of September 6 resulted in 12 people killed.
The Nanmadol typhoon, named after the monument of Micronesian culture — the Nan Madol archaeological site, is slowly moving northwest over waters 217 miles off Japan's southern islands. The pressure in the center of the typhoon is 910 hectopascal (0.8 atm), and the wind speed in the center is 123 miles per hour, with gusts of up to 167 miles per hour.
Officials have issued a typhoon advisory over South Korea's largest island Jeju starting Sunday afternoon. The island may see winds of up to 78 miles per hour and precipitation of up to 80 millimeters. The county's southeastern coastal province Gyeongsang may experience heavy rains up to 150 millimeters and strong winds that will carry on through Monday.