Winter Begins December 21st

It may seem like winter already but the official start of the winter solstice for the Northern Hemisphere begins Saturday, December 21^st and runs until Wednesday, March 19^th. Winter begins when the sun reaches its most southerly declination of -23.5 degrees.

Easier said, the North Pole is tilted 23.5 degrees. The December 21^st or 22^nd winter solstices occur more frequently than the December 20^th and 23^rd solstice. The last December 23^rd solstice was in 1903 and the December 23^rd has occurred very rarely with the next one not due until December 23^rd of 2080.

The varying dates are due to the calendar which has 365 days in a common year and 366 in a leap year. The sun returning to the same position as seen by Earth is different than a calendar year.

Timeanddate.com