Mild spring and autumn are the best time to visit South Korea. As cherries, azaleas, and lotuses are in bloom, April through June is the period when the whole country is dressed up pink, and the national parks are at their finest. However, mind that South Korea is a bit crowded at this time. You should avoid visiting this country in summer because of unbearable mugginess and the monsoon season.
In autumn the rainfall is low and hotel rates are more affordable. September through November is high time to taste hangwa and fresh persimmons. Winter is long and freezingly cold, but worth visiting for its quiet atmosphere, Hwacheon Sancheoneo Ice Festival, and skiing.