South Korea's weather forecasters warned of heavy rains of up to 200 millimeters and strong winds in the country's southern and central regions, as Typhoon Khanun is approaching the southern island of Jeju on Wednesday. 

Khanun, meaning "jack fruit" in Thai, was 490 kilometers south of Seogwipo in the southern part of Jeju as of 6 a.m. on Wednesday and heading northwest along the country's western coast at 20 kilometers per hour, according to the Korea Meteorological Administration.

After passing waters some 80 kilometers off the country's western port city of Gunsan early Thursday, the storm is expected to land near North Korea's Hwanghae Province, it added.  

The typhoon, the country's first tropical one of the season, is middle in scale with central pressure of 988 hectopascals and maximum wind speed of 25 meters per second, the KMA said, adding it is forecast to get weaker later in the day as it passes through warmer waters.   

Heavy downpours and the gale will start on Jeju Island and in the southern part of the country Wednesday afternoon to continue through early Thursday, the KMA said. Up to 200 millimeters of rains are expected in some regions for two days, it added. 

The central and eastern regions, including Seoul, will come under the full power of the tropical storm from late Wednesday, which will bring up to 80 millimeters of rain overnight, according to the forecaster. 

"Heavy rains of 30 millimeters per hour and strong winds of 20 meters per second are expected in some regions," a KMA official said. "Extra precautions are required as the monsoon rains so far have already weakened ground."

The KMA has issued typhoon advisories in Jeju Island and waters off the island to come into effect at 12:00 p.m.

(Yonhap News)