December 1
- National Pie Day
- National Eat a Red Apple Day
- Bifocals at the Monitor Liberation Day
- Day With(out) Art Day
- Rosa Parks Day
- National Package Protection Day – Wednesday after Thanksgiving
December 2
December 3
- National Roof Over Your Head Day
- Faux Fur Friday – First Friday in December
- National Bartender Day – First Friday in December
December 4
- National Cookie Day
- National Dice Day
- National Sock Day
- National Rhubarb Vodka Day – First Saturday in December
- Skywarn Recognition Day – First Saturday in December
December 5
December 6
- National Pawnbrokers Day
- National Microwave Oven Day
- National Gazpacho Day
- St. Nicholas Day
- Miners’ Day
December 7
- National Pearl Harbor Remembrance Day
- National Illinois Day
- National Cotton Candy Day
- World Trick Shot Day – First Tuesday in December
December 8
December 9
December 10
- Dewey Decimal System Day
- National Lager Day
- Human Rights Day
- Nobel Prize Day
- National Salesperson Day – Second Friday in December
- Chanukah Begins – Changes Annually (December 10, 2020)
December 11
December 12
December 13
- National Cocoa Day
- National Violin Day
- National Day of the Horse (Senate Res. 452)
- Pick A Pathologist Pal Day
- National Guard Birthday
December 14
December 15
December 16
December 17
- National Maple Syrup Day
- Wright Brothers Day
- National Ugly Christmas Sweater Day – Third Friday in December
- Underdog Day– Third Friday in December
December 18
- National Twin Day
- National Roast Suckling Pig Day
- Answer The Telephone Like Buddy The Elf Day
- National Wreaths Across America Day – Changes Annually – December 18, 2021
December 19
December 20
December 21
- Crossword Puzzle Day
- Humbug Day
- National Maine Day
- Phileas Fogg Win A Wager Day
- Winter Solstice – Day Between December 20 and 23
- National Flashlight Day – Day of Winter Solstice
- National French Fried Shrimp Day
- National Homeless Persons’ Remembrance Day – First Day of Winter
- Yule – Day of Winter Solstice
- Anne & Samantha Day(also June. 20, 2020)
December 22
- National Date Nut Bread Day
- Forefathers Day – December 22 (Unless on Sunday, Then Following Monday)
December 23
- National Pfeffernusse Day
- National Roots Day
- Festivus
- National Re-Gifting Day – Thursday before Christmas
December 24
December 25
December 26
December 27
December 28
- National Short Film Day
- National Chocolate Candy Day
- National Card Playing Day
- Holy Innocents Day
- Pledge of Allegiance Day
December 29
December 30
December 31
- National Champagne Day
- No Interruptions Day – Last Work Day of the Year
- Leap Second Time Adjustment Day(Note: This is listed as an observance title only. Some years scientists do not make adjustments.But, if they do, then it’s done on either June 30 or December 31.)
- Make Up Your Mind Day
- New Years Eve
- Universal Hour of Peace