December is the twelfth and last month of the year in the Julian and Gregorian Calendars. It is one of seven months with the length of 31 days. December contains the winter solstice in the Northern Hemisphere, the day with the fewest daylight hours, and the summer solstice in the Southern Hemisphere, the day with the most daylight hours (excluding polar regions in both cases). December in the Northern Hemisphere is the seasonal equivalent to June in the Southern Hemisphere and vice versa. In the Northern hemisphere, the beginning of the astronomical winter is traditionally 21 December or the date of the solstice. Meteorological winter begins on 1 December. In the Southern hemisphere, meteorological summer begins on 1 December.