Overview

December 20 is the 354th day of a common year and the 355th day in leap years in the Gregorian calendar. In both common and leap years there are eleven days remaining until the end of the year. The date falls in the final fortnight of December and is often part of the holiday season in many cultures.

Calendar and seasonal context

The day lies immediately before the annual winter solstice in the Northern Hemisphere and the summer solstice in the Southern Hemisphere, so it marks a time of seasonal transition and short daylight hours for much of the north. In ecclesiastical and cultural calendars it typically falls within the season of Advent or the final preparatory days leading to Christmas.

Observances and public commemorations

Several international and national observances fall on or around December 20. Notable examples include:

  • International Human Solidarity Day, designated by the United Nations to promote cooperation and shared responsibility.
  • Various local and national commemorations tied to historical events or civic anniversaries.
  • Cultural customs associated with the broader winter holiday season such as preparations for Christmas and year‑end festivities.

History and notable events

The date has featured in history for political, social, and cultural reasons. A widely remembered event on this day is the 1860 formal secession of South Carolina from the United States, a key step toward the American Civil War. Over time, December 20 has also served as the anniversary date for treaties, declarations, and other national acts in different countries.

Astrology, traditions and distinctions

Astrologically, December 20 is close to the end of the sign of Sagittarius in the tropical zodiac, and the day is often described as on the cusp of the next sign. Meteorologically and culturally, the date occupies a transitional role between ordinary late‑December routines and the concentrated observances of the final ten days of the year. The numbering of the day (354th/355th) reflects calendar conventions and is unaffected by the shift from Julian to Gregorian reckoning except where local adoption dates altered historical dating.

Further reading and references: For general information on leap year rules and the structure of the modern calendar, see resources on leap years and the Gregorian system (leap years, Gregorian calendar).