Seoul, Jan 25 : Cold wave warnings were issued across South Korea on Wednesday as the country came under the grip of the season's coldest weather, authorities said. In Seoul, morning lows plummeted to minus 19.3 degrees Celsius, with an effective temperature of nearly minus 25.7 degrees, as of 6.29 a.m., the Korea Meteorological Administration (KMA) said. A cold wave warning is issued when the morning low is below minus 15 degrees for more than two consecutive days, or when the temperature drops sharply and major damage is expected, Yonhap News Agency reported. Since 2000, Seoul's morning lows have dipped below minus 17 degrees only on nine days, the KMA said. The temperature in mountainous areas of Gangwon province and the northern region of Gyeonggi pdipped to morning lows of minus 25.1 degrees, the KMA said. The freezing temperatures were accompanied by heavy snow in the southern parts of the country, including the resort island of Jeju. More snow is expected throughout the day, with more than 10 cm in the west coastal area of Gyeonggi, and between 5 and 10 cm in mountainous regions on Jeju island, the KMA said. Meanwhile, domestic flight operations in and out of Jeju resumed early Wednesday, airport authorities said. /IANS