| Sat, May 1 | Worker's Day | Multiple [Show] | Public Holiday |
| Sat, May 1 | Batman Day | - | |
| Sat, May 1 | Maharashtra Day | India | State Holiday |
| Sat, May 1 | World Naked Gardening Day | - | Weird |
| Sat, May 1 | National Loyalty Day | - | Weird |
| Sat, May 1 | May Day | - | Weird |
| Sat, May 1 | National Mother Goose Day | - | Weird |
| Sat, May 1 | National Chocolate Parfait Day | - | Weird |
| Sat, May 1 | Law Day | - | Weird |
| Sat, May 1 | School Principals’ Day | - | Weird |
| Sat, May 1 | Silver Star Service Banner Day | - | Weird |
| Sat, May 1 | National Fitness Day | - | Weird |
| Sat, May 1 | National Scrapbook Day | - | Weird |
| Sat, May 1 | National Homebrew Day | - | Weird |
| Sat, May 1 | Join Hands Day | - | Weird |
| Sat, May 1 | National Bombshells’ Day | - | Weird |
| Sat, May 1 | National Start Seeing Monarchs Day | - | Weird |
| Sat, May 1 | Free Comic Book Day | - | Weird |
| Sat, May 1 | National Lemonade Day | - | Weird |
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| Sun, May 2 | National Skilled Trades Day * First Wednesday in May | - | Weird |
| Sun, May 2 | National Truffle Day | - | Weird |
| Sun, May 2 | National Life Insurance Day | - | Weird |
| Sun, May 2 | National Infertility Survival Day | - | Weird |
| Mon, May 3 | National SAN Architect Day | - | Weird |
| Mon, May 3 | National Lumpy Rug Day | - | Weird |
| Mon, May 3 | National Garden Meditation Day | - | Weird |
| Mon, May 3 | National Specially-Able Pets Day | - | Weird |
| Mon, May 3 | National Two Different Colored Shoes Day | - | Weird |
| Mon, May 3 | National Paranormal Day | - | Weird |
| Mon, May 3 | National Chocolate Custard Day | - | Weird |
| Mon, May 3 | National Raspberry Pop Over Day | - | Weird |
| Mon, May 3 | National Textiles Day | - | Weird |
| Mon, May 3 | National Montana Day | - | Weird |
| Mon, May 3 | National Melanoma Monday | - | Weird |
| Tue, May 4 | National Star Wars Day | - | Weird |
| Tue, May 4 | National Weather Observers Day | - | Weird |
| Tue, May 4 | National Renewal Day | - | Weird |
| Tue, May 4 | National Orange Juice Day | - | Weird |
| Tue, May 4 | National Candied Orange Peel Day | - | Weird |
| Tue, May 4 | National Foster Care Day | - | Weird |
| Tue, May 4 | National Teacher Appreciation Day | - | Weird |
| Tue, May 4 | Coronation Day | Thailand | National Holiday |
| Wed, May 5 | National Astronaut Day | - | Weird |
| Wed, May 5 | National Cartoonists Day | - | Weird |
| Wed, May 5 | National Silence the Shame Day | - | Weird |
| Wed, May 5 | National Totally Chipotle Day | - | Weird |
| Wed, May 5 | National Hoagie Day | - | Weird |
| Wed, May 5 | Cinco de Mayo | - | Weird |
| Wed, May 5 | National School Nurse Day | - | Weird |
| Thu, May 6 | National Nurses Day | United states | Observance |
| Thu, May 6 | International No Diet Day | - | Weird |
| Thu, May 6 | National Beverage Day | - | Weird |
| Thu, May 6 | National Crepe Suzette Day | - | Weird |
| Thu, May 6 | National Day of Reason | - | Weird |
| Thu, May 6 | World Password Day | - | Weird |
| Thu, May 6 | National Day of Prayer | United states | Observance |
| Fri, May 7 | National Packaging Design Day | - | Weird |
| Fri, May 7 | National Paste-Up Day | - | Weird |
| Fri, May 7 | National Barrier Awareness Day | - | Weird |
| Fri, May 7 | National Roast Leg of Lamb Day | - | Weird |
| Fri, May 7 | National Space Day | - | Weird |
| Fri, May 7 | School Lunch Hero Day | - | Weird |
| Fri, May 7 | National Military Spouse Appreciation Day | - | Weird |
| Fri, May 7 | National Provider Appreciation Day | - | Weird |
| Fri, May 7 | No Pants Day | - | Weird |
| Sat, May 8 | National Coconut Cream Pie Day | - | Weird |
| Sat, May 8 | National Have A Coke Day | - | Weird |
| Sat, May 8 | National Birth Mother’s Day | - | Weird |
| Sat, May 8 | National Babysitter’s Day | - | Weird |
| Sat, May 8 | National Dog Mom’s Day | - | Weird |
| Sat, May 8 | National Train Day | - | Weird |
| Sat, May 8 | National Archery Day | - | Weird |
| Sat, May 8 | National Miniature Golf Day | - | Weird |
| Sat, May 8 | Cornelia De Lange Syndrome Awareness Day | - | Weird |
| Sat, May 8 | Stamp Out Hunger Food Drive Day | - | Weird |
| Sun, May 9 | National Lost Sock Memorial Day | - | Weird |
| Sun, May 9 | National Moscato Day | - | Weird |
| Sun, May 9 | National Butterscotch Brownie Day | - | Weird |
| Sun, May 9 | National Sleepover Day | - | Weird |
| Mon, May 10 | National Clean Up Your Room Day | - | Weird |
| Mon, May 10 | National Lipid Day | - | Weird |
| Mon, May 10 | National Shrimp Day | - | Weird |
| Mon, May 10 | National Washington Day | - | Weird |
| Mon, May 10 | National Women’s Checkup Day | - | Weird |
| Tue, May 11 | National Eat What You Want Day | - | Weird |
| Tue, May 11 | National Foam Rolling Day | - | Weird |
| Tue, May 11 | National Twilight Zone Day | - | Weird |
| Wed, May 12 | International Nurses Day | - | International |
| Wed, May 12 | National Limerick Day | - | Weird |
| Wed, May 12 | National Odometer Day | - | Weird |
| Wed, May 12 | National Nutty Fudge Day | - | Weird |
| Wed, May 12 | National Fibromyalgia Awareness Day | - | Weird |
| Wed, May 12 | National Receptionists’ Day | - | Weird |
| Wed, May 12 | National Third Shift Workers Day | - | Weird |
| Thu, May 13 | National Crouton Day | - | Weird |
| Thu, May 13 | National Frog Jumping Day | - | Weird |
| Thu, May 13 | National Apple Pie Day | - | Weird |
| Thu, May 13 | National Fruit Cocktail Day | - | Weird |
| Fri, May 14 | National Decency Day * | - | Weird |
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| Fri, May 14 | National Dance Like a Chicken Day | - | Weird |
| Fri, May 14 | National Underground America Day | - | Weird |
| Fri, May 14 | National Buttermilk Biscuit Day | - | Weird |
| Fri, May 14 | Akshaya Tritiya | - | Hindu |
| Sat, May 15 | Peace Officers Memorial Day | - | Weird |
| Sat, May 15 | National Chocolate Chip Day | - | Weird |
| Sat, May 15 | National Nylon Stocking Day | - | Weird |
| Sat, May 15 | National Learn to Swim Day | - | Weird |
| Sun, May 16 | Honor Our LGBT Elders Day | - | Weird |
| Sun, May 16 | National Do Something Good for Your Neighbor Day | - | Weird |
| Sun, May 16 | National Love a Tree Day | - | Weird |
| Sun, May 16 | National Piercing Day | - | Weird |
| Sun, May 16 | National Sea Monkey Day | - | Weird |
| Sun, May 16 | National Biographer’s Day | - | Weird |
| Sun, May 16 | National Coquilles Saint Jacques Day | - | Weird |
| Sun, May 16 | Take Your Parents To The Playground Day | - | Weird |
| Mon, May 17 | National Pack Rat Day | - | Weird |
| Mon, May 17 | National Cherry Cobbler Day | - | Weird |
| Mon, May 17 | National Graduation Tassel Day | - | Weird |
| Mon, May 17 | National Walnut Day | - | Weird |
| Mon, May 17 | National Idaho Day | - | Weird |
| Tue, May 18 | National HIV Vaccine Awareness Day | - | Weird |
| Tue, May 18 | National Visit Your Relatives Day | - | Weird |
| Tue, May 18 | National No Dirty Dishes Day | - | Weird |
| Tue, May 18 | National Cheese Soufflé Day | - | Weird |
| Wed, May 19 | National May Ray Day | - | Weird |
| Wed, May 19 | National Devil’s Food Cake Day | - | Weird |
| Wed, May 19 | Emergency Medical Services for Children Day | - | Weird |
| Thu, May 20 | National Be a Millionaire Day | - | Weird |
| Thu, May 20 | National Pick Strawberries Day | - | Weird |
| Thu, May 20 | National Rescue Dog Day | - | Weird |
| Thu, May 20 | National Quiche Lorraine Day | - | Weird |
| Fri, May 21 | National American Red Cross Founder’s Day | - | Weird |
| Fri, May 21 | National Waitstaff Day | - | Weird |
| Fri, May 21 | National Strawberries and Cream Day | - | Weird |
| Fri, May 21 | National Memo Day | - | Weird |
| Fri, May 21 | National Bike to Work Day | - | Weird |
| Fri, May 21 | National Endangered Species Day | - | Weird |
| Fri, May 21 | National Defense Transportation Day | - | Weird |
| Fri, May 21 | National Pizza Party Day | - | Weird |
| Fri, May 21 | NASCAR Day | - | Weird |
| Sat, May 22 | National Craft Distillery Day * | - | Weird |
| Sat, May 22 | National Maritime Day | - | Weird |
| Sat, May 22 | National Solitaire Day | - | Weird |
| Sat, May 22 | National Buy a Musical Instrument Day | - | Weird |
| Sat, May 22 | National Vanilla Pudding Day | - | Weird |
| Sun, May 23 | World Turtle Day | - | Weird |
| Sun, May 23 | National Lucky Penny Day | - | Weird |
| Sun, May 23 | National Taffy Day | - | Weird |
| Mon, May 24 | National Aviation Maintenance Technician Day | - | Weird |
| Mon, May 24 | Brother’s Day | - | Weird |
| Mon, May 24 | National Scavenger Hunt Day | - | Weird |
| Mon, May 24 | National Escargot Day | - | Weird |
| Mon, May 24 | National Wyoming Day | - | Weird |
| Tue, May 25 | Towel Day | - | Weird |
| Tue, May 25 | National Wine Day | - | Weird |
| Tue, May 25 | National Missing Children’s Day | - | Weird |
| Tue, May 25 | National Tap Dance Day | - | Weird |
| Tue, May 25 | National Brown-Bag It Day | - | Weird |
| Wed, May 26 | National Blueberry Cheesecake Day | - | Weird |
| Wed, May 26 | National Senior Health & Fitness Day | - | Weird |
| Wed, May 26 | Buddha Purnima/Vesak | Multiple [Show] | Multiple Types |
| Wed, May 26 | Buddha Purnima | Pakistan | Optional Holiday |
| Thu, May 27 | National Cellophane Tape Day | - | Weird |
| Thu, May 27 | National Grape Popsicle Day | - | Weird |
| Fri, May 28 | Hamburger Day | - | Weird |
| Fri, May 28 | National Brisket Day | - | Weird |
| Fri, May 28 | National Don’t Fry Day | - | Weird |
| Fri, May 28 | National Heat Awareness Day | - | Weird |
| Sat, May 29 | National Paperclip Day | - | Weird |
| Sat, May 29 | National Coq Au Vin Day | - | Weird |
| Sun, May 30 | National Creativity Day | - | Weird |
| Sun, May 30 | National Water a Flower Day | - | Weird |
| Sun, May 30 | National Hole In My Bucket Day | - | Weird |
| Sun, May 30 | National Mint Julep Day | - | Weird |
| Sun, May 30 | Loomis Day | - | Weird |
| Sun, May 30 | Harvest Festival | Malaysia | Common Local Holidays |
| Mon, May 31 | World No Tobacco Day | - | International |
| Mon, May 31 | Autonomous Vehicle Day | - | Weird |
| Mon, May 31 | National Save Your Hearing Day | - | Weird |
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| Mon, May 31 | National Speak in Sentences Day | - | Weird |
| Mon, May 31 | National Macaroon Day | - | Weird |
| Mon, May 31 | National Utah Day | - | Weird |
| Mon, May 31 | National Smile Day | - | Weird |
| Mon, May 31 | Necrotizing Fasciitis Awareness Day | - | Weird |
| Mon, May 31 | Spring Bank Holiday | Multiple [Show] | Multiple Types |
