Korea has four distinct seasons. In summer, it is hot and humid. It is a Korean custom to choose the three hottest days of the summer and to eat especially healthy food on those days.
Boknal (복날) is known as the Three Dog Days of Summer. The first day is known as Chobok (초복), the second day is Jungbok (중복), and the third day is known as Malbok (말복). These days are predetermined by the lunar calendar. This year, the first day was on July 13, 2013.