December Solstice is the winter solstice in the Northern Hemisphere, when it is the darkest day of the year. In the Southern Hemisphere, it is the summer solstice and the longest daylight day of the year.

December Solstice occurs when the Sun reaches its most southerly declination of 23.4 degrees or it means that when the North Pole is tilted furthest away from the Sun. While people in the Northern Hemisphere experience the fewest hours of daylight or no direct sunlight from north of the Arctic Circle towards the North Pole, people in the Southern Hemisphere, south of the Antarctic Circle towards the South Pole see the Midnight Sun or 24 hours of daylight.

December Solstice happens around 20, 21, 22 or 23 of December, more often on 21 or 22 rather than 20 and 23. The last December 23 solstice was in 1903 and the next one is on 2303. A December 20 solstice is very rare, the next one is in 2080. The difference in the dates of solstice vary because of the calendar system, in which there are 365 days in a common year and 366 days in a leap year. The dates also vary because of the orbital and daily rotational motion of the Earth.

December Solstice is important to the cultures worldwide since ancient times until today. Christmas celebrations are closely linked to the observance of the December solstice.