Here is a list with links to strange, fun and unofficial holidays celebrated in September. Links in boldface are profiled on Worldwide Weird Holidays.
September 1
Chicken Boy Day
Wisconsin State Cow Chip Throw – 2017 – Labor Day weekend
American Chess Day
Building and Code Staff Appreciation Day
Calendar Adjustment Day
Emma M. Nutt Day
National Cherry Popover Day
National No Rhyme or Reason Day
Pink Cadillac Day
Toy Tips Executive Toy Test Day
September 2
International Bacon Day – 2017 – Saturday before Labor Day
National Blueberry Popsicle Day
National Lazy Mom’s Day
Pierce Your Ears Day
Spalding Baseball Day
Victory over Japan Day
Wear Teal Day
September 3
Franchise Appreciation Day
International Vulture Awareness Day – 2016
National Hummingbird Day
National Skyscraper Day
National Welsh Rarebit Day
US Bowling League Day
World Beard Day
September 4
Eat an Extra Dessert Day
National Macadamia Nut Day
National Newspaper Carrier Day
National Wildlife Day
September 5
National Be Late For Something Day
National Cheese Pizza Day
National Shrink Day
September 6
Fight Procrastination Day
Another Look Unlimited Day
Barbie Doll Day
Great Egg Toss Day
National Coffee Ice Cream Day
Read a Book Day
September 7
National Buy a Book Day
Google Commemoration Day
Grandma Moses Day
National Acorn Squash Day
National Feel the Love Day
National Neither Rain Nor Snow Day
Salami Day
September 8
Pardon Day
International Literacy Day
National Date Nut Bread Day
National Pledge of Allegiance Day
Pediatric Hematology/Oncology Nurses Day
Virgin Mary Day
World Physical Therapy Day
September 9
Tester’s Day
Fetal Alcohol Spectrum Disorders Awareness Day
International Sudoku Day
National Hug Your Boss Day
National Steak au Poivre Day
National Teddy Bear Day
National Wiener Schnitzel Day
Stand up to Cancer Day
Wonderful Weirdos Day
September 10
International Creepy Boston Dynamics Robotic Horse Day
Aunt’s Day
Blame It on the Large Hadron Collider Day
Carl Garner Federal Lands Cleanup Day
Farmers’ Consumer Awareness Day
International Drive Your Studebaker Day
International Make-Up Day
National Hot Dog Day
National Iguana Awareness Day
National Lacemaking Day
National Swap Ideas Day
Sew Be It Day
TV Dinner Day
World First Aid Day
World Suicide Prevention Day
September 11
“I Want to Start My Own Business” Day
Libraries Remember Day
Make Your Bed Day
National Day of Service and Remembrance
National Emergency Responders Day
National Grandparent’s Day
National Hot Cross Bun Day
National Hug Your Hound Day
National No News Is Good News Day
National Pet Memorial Day
Patriot Day
Sustainable House Day
Women’s Baseball Day
September 12
National Video Games Day
I’m on Top of It Day
International Day for South-South Cooperation
National Boss/Employee Exchange Day
National Chocolate Milkshake Day
National Day of Encouragement
National Police Woman Day
Programmers’ Day
September 13
Roald Dahl Day
Bald is Beautiful Day
Fortune Cookie Day
International Chocolate Day
Kids Take Over The Kitchen Day
National Celiac Awareness Day
National Defy Superstition Day
National Peanut Day
Positive Thinking Day
Snack a Pickle Day
Uncle Sam Day
September 14
National Cream-Filled Donut Day
Eat a Hoagie Day
National Coloring Day
September 15
Google.com Day
Greenpeace Day
International Day of Democracy
International Dot Day
Make a Hat Day
National Caregivers Day
National Crème de Menthe Day
National Felt Hat Day
National Linguine Day
National Thank You Day
Someday
September 16
World Play-Doh Day
Anne Bradstreet Day
International Day for the Preservation of the Ozone Layer
Mayflower Day
Mexican Independence Day
National Cinnamon Raisin Bread Day
National Collect Rocks Day
National Day of Prayer and Remembrance for the Victims of Hurricane Katrina
National Guacamole Day
National POW/MIA Recognition Day
National Stay Away From Seattle Day
National Tattoo Story Day
National Tradesmen Day
Stepfamily Day
Trail of Tears Commemoration Day
Working Parents Day
Wrinkled Raincoat Day
September 17
International Eat an Apple Day – 2016
Big Whopper Liar Day
Boys’ and Girls’ Club Day for Kids
Constitution Day
International Coastal Cleanup Day
National Apple Dumpling Day
National Gymnastics Day
Puppy Mill Awareness Day
Responsible Dog Ownership Day
Software Freedom Day
Time’s Up Day
September 18
Chiropractic Founders Day
Hug a Greeting Card Writer Day
International Read an eBook Day
National Cheeseburger Day
National HIV/AIDS and Aging Awareness Day
National Neighborhood Day
National Respect Day
National Wife Appreciation Day
National Women’s Friendship Day
Rice Krispies Treats Day
World Bamboo Day
World Water Monitoring Day
September 19
International Talk Like a Pirate Day
National Butterscotch Pudding Day
National Woman Road Warrior Day
September 20
National Gibberish Day
National Punch Day
September 21
Miniature Golf Day
International Banana Festival
International Day of Peace
National Farm Safety Day for Kids
National Pecan Cookie Day
National School Backpack Awareness Day
Pause the World Day
World Alzheimer’s Day
World Gratitude Day
September 22
Hobbit Day
Business Women’s Day
Dear Diary Day
International Day of Radiant Peace
National Centenarian’s Day
National Elephant Appreciation Day
National Ice Cream Cone Day
National White Chocolate Day
Proposal Day
The First Day of Fall
World Carfree Day
World Rhino Day
September 23
Checkers Day
Celebrate Bisexuality Day
Great American Pot Pie Day
Innergize Day
Love Note Day
Native American Day
Restless Legs Awareness Day
See You at the Pole
September 24
Family Health and Fitness Day USA
Festival of Latest Novelties
Fish Amnesty Day
Gallbladder Good Health Day
International Lace Day
International Rabbit Day
Kiss Day
Kiwanis Kids’ Day
National Bluebird of Happiness Day
National Cherries Jubilee Day
National Hunting and Fishing Day
National Museum Day
National Public Lands Day
National Punctuation Day
National Seat Check Saturday
National Wildlife Ecology Day
R.E.A.D. in America Day
Schwenkfelder Thanksgiving
September 25
Daughter’s Day
Gold Star Mother’s Day
International Ataxia Awareness Day
Math Storytelling Day
National Comic Book Day
National Cooking Day
National Crab Meat Newburg Day
National Food Service Employees Day
National Lobster Day
National One-Hit Wonder Day
National Psychotherapy Day
National One-Hit Wonder Day
World Deaf Day
World Dream Day
World Pharmacist Day
World Rivers Day – last Sunday
September 26
Presidential Debate Day
European Day of Languages
Family Day
Johnny Appleseed Day
Lumberjack Day
National Better Breakfast Day
National Pancake Day
Shamu the Whale Day
September 27
Ancestor Appreciation Day
National Chocolate Milk Day
National Corned Beef Hash Day
National Crush a Can Day
National Gay Men’s HIV/AIDS Awareness Day
National Voter Registration Day
World Tourism Day
September 28
Fish Tank Floorshow Night
International Right to Know Day
National Ask a Stupid Question Day
National Drink Beer Day
National Good Neighbor Day
National Strawberry Cream Pie Day
National Women’s Health and Fitness Day
Read a Child a Book You Like Day
World Rabies Day
World School Milk Day
September 29
Broadway Musicals Day
Confucius Day
Happy Goose Day
Michaelmas
National Attend Your Grandchild’s Birthday Day
National Coffee Day
National Mocha Day
National Poisoned Blackberries Day
VFW Day
World Heart Day
World Maritime Day
September 30
Blasphemy Day
Chewing Gum Day
Hug a Vegetarian Day
International Translation Day
National Mud Pack Day
National Mulled Cider Day
Save the Koala Day
The Time for Yoga