Winter continues throughout South Korea in February. It is typically the coldest month of the year and it will feel especially cold in the country's mountainous National Parks where temperatures can occasionally drop to -20°C.
Wherever you are in South Korea, you can expect freezing temperatures and frequent snowfall: good news if you're planning to visit the ski resorts of Yongpyong and Alpensia in the heart of Gangwon-do province. It's no surprise that Pyeongchang (in this northern province) is hosting the 2018 Winter Olympics during February.
The temperature does not rise above freezing in Seoul. Even in the mildest areas of the country, on its southern coast, there is more than a nip in the air: Jeju Island typically records a minimum of 3°C and a maximum of 8°C during February.
The winter is, however, mercifully dry, so there will be very little rainfall.