Thermal underwear and pajamas are selling well due to an early cold spell that hit the country.
Online shopping site Gmarket said Wednesday that sales of thermal underwear in the past month were up 51 percent on-year.
GS Shop, which started selling thermal underwear on its shopping channel from mid-November, saw their sales rise by more than 20 percent compared to a year ago.
Wearing thermal underwear has an effect of raising the body temperature by some 2.5 degrees Celsius, and more young people opt to wear thermal pajamas to sleep.
"We expect sales to more than double in December from the previous month," said a GS staffer.