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

December 2

• National Fritters Day
• National Mutt Day
• Special Education Day 
• Cyber Monday – Monday After Thanksgiving

December 3

• National Roof Over Your Head Day
• World Trick Shot Day – First Tuesday in December
• National Day of Giving – #GivingTuesday – Usually Follows Cyber Monday

December 4

• National Cookie Day
• National Dice Day
• National Sock Day
• National Package Protection Day – Wednesday after Thanksgiving

December 5

• National Sacher Torte Day
• AFL-CIO Day
• Bathtub Party Day
• International Ninja Day
• National Repeal Day

December 6

• National Pawnbrokers Day
• National Microwave Oven Day
• National Gazpacho Day
• St. Nicholas Day
• Miners’ Day
• Faux Fur Friday – First Friday in December

December 7

• National Pearl Harbor Remembrance Day
• National Illinois Day
• National Cotton Candy Day
• National Rhubarb Vodka Day – First Saturday in December
• Skywarn Recognition Day – First Saturday in December

December 8

• National Brownie Day
• Pretend To Be A Time Traveler Day

December 9

• National Pastry Day
• Weary Willie Day

December 10

• Dewey Decimal System Day
• National Lager Day
• Human Rights Day
• Nobel Prize Day

December 11

• National App Day
• National Noodle Ring Day

December 12

• National Ambrosia Day
• National Ding-a-Ling Day
• Gingerbread House Day
• Poinsettia Day

December 13

• National Cocoa Day
• National Violin Day
• National Day Of The Horse  (Senate Res. 452)
• Pick A Pathologist Pal Day
• National Guard Birthday
• National Salesperson Day – Second Friday in December

December 14

• National Bouillabaisse Day
• National Alabama Day
• Monkey Day
• National Wreaths Across America Day – Changes Annually – December 14, 2019

December 15

• National Cupcake/ Lemon Cupcake Day
• Bill of Rights Day
• Cat Herders Day
• National Wear Your Pearls Day

December 16

• National Chocolate-covered Anything Day
• Barbie and Barney Backlash Day

December 17

• National Maple Syrup Day
• Wright Brothers Day

December 18

• National Roast Suckling Pig Day
• Answer The Telephone Like Buddy The Elf Day

December 19

• National Hard Candy Day
• National Oatmeal Muffin Day
• National Re-Gifting Day – Thursday before Christmas

December 20

• National Sangria Day
• Mudd Day
• National Ugly Christmas Sweater Day – Third Friday in December
• Underdog Day– Third Friday in December

December 21 

• National French Fried Shrimp Day
• 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 Homeless Persons’ Remembrance Day – First Day of Winter
• Yule – Day of Winter Solstice

December 22

• National Date Nut Bread Day
• Anne & Samantha Day(also June. 21)

December 23

• National Pfeffernusse Day
• National Roots Day
• Festivus
• Forefathers Day – December 22 (Unless on Sunday, Then Following Monday)
• Chanukah Begins – Changes Annually

December 24

• National Eggnog Day
• Christmas Eve

December 25

• National Pumpkin Pie Day
• A’Phabet Day or No “L” Day
• Christmas

December 26

• National Candy Cane Day
• National Thank-you Note Day
• National Whiner’s Day
• Boxing Day (Canada)

December 27

• National Fruitcake Day

December 28

• National Short Film Day *
• National Chocolate Candy Day
• National Card Playing Day
• Holy Innocents Day
• Pledge of Allegiance Day

December 29

• National Pepper Pot Day
• Tick Tock Day

December 30

• National Bicarbonate of Soda Day
• Falling Needles Family Fest Day
• Bacon Day

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