May 1st
- National Loyalty Day
- May Day
- National Mother Goose Day
- National Chocolate Parfait Day
- Law Day
- School Principals’ Day
- Silver Star Service Banner Day
- Kentucky Derby – First Saturday in May
- National Fitness Day – First Saturday in May
- National Scrapbook Day – First Saturday in May
- National Homebrew Day – First Saturday in May
- Join Hands Day – First Saturday in May
- National Bombshells’ Day – First Saturday in May
- National Start Seeing Monarchs Day – First Saturday in May
- Free Comic Book Day – First Saturday in May
- National Play Outside Day – First Saturday of Every Month
May 2nd
- National Truffle Day
- National Life Insurance Day
- National Infertility Survival Day – Sunday Before Mother’s Day
- National Lemonade Day – First Sunday in May
May 3rd
- National SAN Architect Day
- National Lumpy Rug Day
- National Garden Meditation Day
- National Specially-Able Pets Day
- National Two Different Colored Shoes Day
- National Paranormal Day
- National Chocolate Custard Day
- National Raspberry Pop Over Day
- National Textiles Day
- National Montana Day
- Melanoma Monday – First Monday in May
May 4th
- National Star Wars Day
- National Weather Observers Day
- National Renewal Day
- National Orange Juice Day
- National Candied Orange Peel Day
- Bird Day
- National Foster Care Day – First Tuesday in May
- National Teacher Appreciation Day – Tuesday of the First Full Week in May
May 5th
- National Astronaut Day
- National Cartoonists Day
- National Silence the Shame Day
- National Totally Chipotle Day
- National Hoagie Day
- Cinco de Mayo
- National Bike To School Day – Changes Annually May 5, 2021
- National Skilled Trades Day – First Wednesday in May
- National Interpreter Appreciation Day – First Wednesday in May
May 6th
- National Nurses Day
- National Beverage Day
- National Crepe Suzette Day
- National Day of Prayer – First Thursday in May
- National Day of Reason – First Thursday in May
- World Password Day – First Thursday in May
May 7th
- National Packaging Design Day
- National Paste-Up Day
- National Barrier Awareness Day
- National Roast Leg of Lamb Day
- National Military Spouse Appreciation Day – Friday Before Mother’s Day
- National Provider Appreciation Day – Friday Before Mother’s Day
- National Space Day – First Friday in May
- School Lunch Hero Day – First Friday in May
May 8th
- National Coconut Cream Pie Day
- National Have A Coke Day
- National Student Nurse Day
- National Birth Mother’s Day – Saturday before Mother’s Day
- National Babysitter’s Day – Saturday before Mother’s Day
- National Dog Mom’s Day – Second Saturday in May
- National Train Day – Saturday Closest to May 10
- National Archery Day – Second Saturday in May
- National Miniature Golf Day – Second Saturday in May
- Cornelia De Lange Syndrome Awareness Day – Second Saturday in May
- Stamp Out Hunger Food Drive Day – Second Saturday in May
May 9th
- National Lost Sock Memorial Day
- National Moscato Day
- National Butterscotch Brownie Day
- National Sleepover Day
- Mother’s Day – Second Sunday in May
May 10th
- National Clean Up Your Room Day
- National Lipid Day
- National Shrimp Day
- National Washington Day
- National Women’s Checkup Day – Second Monday in May
May 11th
May 12th
- National Limerick Day
- National Odometer Day
- National Nutty Fudge Day
- National Fibromyalgia Awareness Day
- National Receptionists’ Day – Second Wednesday in May
- National Third Shift Workers Day – Second Wednesday in May
- National School Nurse Day – Wednesday of National Nurses Week
May 13th
May 14th
- National Decency Day
- National Dance Like a Chicken Day
- National Underground America Day
- National Buttermilk Biscuit Day
May 15th
- Peace Officers Memorial Day
- National Chocolate Chip Day
- National Nylon Stocking Day
- National Armed Forces Day – Third Saturday in May
- National Learn to Swim Day – Third Saturday in May
May 16th
- Honor Our LGBT Elders Day
- National Barbecue Day
- National Do Something Good for Your Neighbor Day
- National Love a Tree Day
- National Mimosa Day
- National Piercing Day
- National Sea Monkey Day
- National Biographer’s Day
- National Coquilles Saint Jacques Day
- Take Your Parents To The Playground Day – Third Sunday in May
May 17th
- National Pack Rat Day
- National Cherry Cobbler Day
- National Graduation Tassel Day
- National Walnut Day
- National Idaho Day
May 18th
- National HIV Vaccine Awareness Day
- National Visit Your Relatives Day
- National No Dirty Dishes Day
- National Cheese Soufflé Day
May 19th
- National May Ray Day
- National Devil’s Food Cake Day
- Emergency Medical Services for Children Day – Wednesday of Emergency Medical Service Week
- National Juice Slush Day – Third Wednesday In May
May 20th
- National Be a Millionaire Day
- National Pick Strawberries Day
- National Rescue Dog Day
- National Quiche Lorraine Day
May 21st
- National American Red Cross Founder’s Day
- National Waitstaff Day
- National Strawberries and Cream Day
- National Memo Day
- National Endangered Species Day – Third Friday in May
- National Defense Transportation Day – Third Friday in May
- National Pizza Party Day – Third Friday in May
- National Bike to Work Day – Third Friday in May
- NASCAR Day – Third Friday in May
May 22nd
- National Craft Distillery Day
- World Paloma Day
- National Maritime Day
- National Solitaire Day
- National Buy a Musical Instrument Day
- National Vanilla Pudding Day
May 23rd
May 24th
- National Yucatan Shrimp Day
- National Aviation Maintenance Technician Day
- Brother’s Day
- National Scavenger Hunt Day
- National Escargot Day
- National Wyoming Day
May 25th
- National Missing Children’s Day
- National Tap Dance Day
- National Brown-Bag It Day
- Towel Day
- National Wine Day
May 26th
- National Blueberry Cheesecake Day
- National Paper Airplane Day
- National Senior Health & Fitness Day – Last Wednesday in May
May 27th
May 28th
- National Beef Burger Day
- National Brisket Day
- National Hamburger Day
- National Don’t Fry Day – Friday Before Memorial Day
- National Road Trip Day – Friday Before Memorial Day
- National Cooler Day – Friday Before Memorial Day
May 29th
May 30th
- National Creativity Day
- National Water a Flower Day
- National Hole In My Bucket Day
- National Mint Julep Day
- Loomis Day
- World Multiple Sclerosis Day
May 31st
- Autonomous Vehicle Day
- National Save Your Hearing Day
- National Speak in Sentences Day
- National Macaroon Day
- National Utah Day
- National Smile Day
- Necrotizing Fasciitis Awareness Day
- National Memorial Day – Last Monday in May
*Proclamation for a New Day in 2021
