August 10, 2026, is the 222nd day of the year, with 143 days remaining, and it falls on a Monday — in the thirty-third week of the year.
August 10 includes 15 national and international observances, three of which mark notable historical anniversaries. Smithsonian Day celebrates the 180th anniversary of the institution’s founding in 1846. International Biodiesel Day marks the 133rd anniversary of Rudolf Diesel’s peanut oil engine test in 1893. Agent Orange Awareness Day commemorates the start of Operation Ranch Hand on August 10, 1961.
World Lion Day sends an urgent conservation message, since fewer than 25,000 wild lions remain. National Lazy Day happens to fall on a Monday this year, a fittingly ironic bit of timing, and s’mores are essentially required.
National Days on August 10
All national & international days celebrated today
15 celebrations on this dayNational S’mores Day
National S’mores Day honors the classic campfire treat, a toasted marshmallow and a square of chocolate pressed between two graham crackers. It was first documented in a 1927 Girl Scout handbook, where the recipe was called Some More, a name campers soon shortened into a single word that captured exactly what they wanted more of. The s’more remains the defining food of American summer nights around a fire. Its simple three-ingredient makeup belies the reliable joy it brings.
Smithsonian Day
Smithsonian Day on August 10 marks the anniversary of the founding of the Smithsonian Institution on August 10, 1846. Congress established the institution through an act using a bequest from British scientist James Smithson, who left his estate to the United States to create an institution for the increase and diffusion of knowledge. Today the Smithsonian is the world’s largest museum and research complex. It encompasses 19 museums, 21 libraries, 9 research centers, and more than 155 million objects.
World Lion Day
World Lion Day was founded in 2013 by Big Cat Rescue and is observed each year on August 10. It raises awareness of the dramatic decline in wild lion populations, which have fallen from an estimated 200,000 a century ago to fewer than 25,000 today. Lions are now extinct in 26 African countries and across most of their historic range. The day advocates for habitat protection, reduced human-wildlife conflict, and an end to trophy hunting and captive lion breeding operations.
International Biodiesel Day
International Biodiesel Day is observed on August 10, marking the anniversary of a milestone in 1893, when Rudolf Diesel’s engine first successfully ran on peanut oil and demonstrated the viability of vegetable-based fuels. The day raises awareness of biodiesel as a renewable, cleaner-burning alternative to petroleum diesel. Made from vegetable oils, animal fats, or recycled cooking grease, biodiesel can reduce lifecycle carbon emissions by up to 74% compared to fossil diesel.
Here’s every observance celebrated on August 10, 2026.
National & International Days on August 10
Whether you’re eating s’mores, visiting the Smithsonian, being lazy, appreciating lions and Duran Duran, vlogging, spoiling your dog, updating your bio, toasting biodiesel, raising a SKI Citrus Soda, celebrating Connecticut, admiring skyscrapers, honouring Herbert Hoover, or reflecting on Agent Orange, here’s the story behind each of these August 10 celebrations.
Agent Orange Awareness Day
Agent Orange Awareness Day commemorates the first known use of Agent Orange during the Vietnam War on August 10, 1961. This herbicide, used to defoliate forests and reveal enemy positions, left a devastating legacy. Exposure to its dioxin contaminant has caused severe health issues in both American veterans and Vietnamese civilians. First promoted in 1988, the day encourages those affected to seek support and raises awareness about the ongoing consequences through advocacy by organizations such as the Vietnam Veterans Memorial Fund and Soldiers’ Angels.
Duran Duran Appreciation Day
Duran Duran Appreciation Day celebrates the iconic English band known for shaping the new wave and synth-pop era. While its exact origin is unclear, the day gained popularity after being publicized by YM Magazine in 2003. Some say it was created by a Michigan radio DJ who shared a birthday with the date; others link it to a 1985 boating accident involving lead singer Simon Le Bon. Regardless, fans around the world use August 10 to revisit Duran Duran’s influential music and legacy.
International Biodiesel Day
International Biodiesel Day commemorates August 10, 1893, when Rudolf Diesel successfully ran an engine using peanut oil as fuel. This unofficial holiday highlights the environmental benefits of biodiesel and promotes cleaner, renewable alternatives to traditional fossil fuels. The day also raises awareness about innovation in sustainable energy solutions and honors the pioneers who helped make it possible.
International Vlogging Day
International Vlogging Day was founded in 2018 by Summer in the City—now known as Social in the City—to celebrate the growing impact of video blogging. As one of the UK’s largest online video festivals, the event aimed to recognize the power of storytelling, community-building, and creative expression through vlogging. August 10 serves as a tribute to content creators worldwide and encourages people to share their own voices through video.
National Connecticut Day
National Connecticut Day recognizes the fifth state to join the United States and its long-standing influence on American history and innovation. Known as the “Constitution State,” Connecticut adopted the Fundamental Orders in 1639—considered by many to be the first written constitution in the Western world. From early revolutionary leaders like Roger Sherman to world-class institutions such as Yale University, the state blends colonial heritage, maritime culture, and industrial innovation in its contributions to the nation.
National Lazy Day
National Lazy Day offers a guilt-free reason to slow down and enjoy some well-deserved rest. Though its origins remain unknown, this unofficial holiday has grown in popularity as a reminder to prioritize self-care, unplug from constant activity, and simply be. Whether it’s lounging in bed, reading a book, or taking a nap, National Lazy Day encourages relaxation in all its forms.
National S’mores Day
National S’mores Day celebrates the iconic campfire treat made with graham crackers, chocolate, and toasted marshmallows. While the exact origins of s’mores are unclear, the first published recipe appeared in the 1927 Tramping and Trailing with the Girl Scouts handbook. Earlier reports suggest Girl Scout groups had already been enjoying them as early as 1925. The treat was originally called “Some Mores,” which eventually evolved into “s’mores.” Though entrepreneur Alec Barnum is sometimes credited with popularizing the snack, it’s the Girl Scouts who gave it a lasting place in American culinary tradition.
National Shapewear Day
National Shapewear Day was founded in 2017 by The Pink Room to celebrate the evolution of shapewear and its role in boosting body confidence. The day honors the long history of foundation garments—from corsets to modern sculpting wear—and acknowledges the ways shapewear can help individuals feel more comfortable and empowered in their own skin. It also shines a light on industry innovation and the growing diversity of shapewear designs to suit all body types and needs.
National SKI Citrus Soda Day
National SKI Citrus Soda Day honors the lemon-orange flavored soft drink SKI, first introduced on August 10, 1956. The Double Cola Company created this observance in 2020 to celebrate the soda’s loyal fan base and distinct flavor made with real citrus concentrates. With its bold taste and caffeine boost, SKI has earned a dedicated following across parts of the U.S., especially in the South and Midwest.
National Spoil Your Dog Day
National Spoil Your Dog Day is a celebration of the bond between humans and their canine companions. Whether dogs serve as working animals or beloved pets, the day encourages extra treats, cuddles, and attention. It’s part of a wider trend of dog-themed observances, such as National Walking the Dog Day and Take Your Dog to Work Day. Today serves as a heartfelt reminder of the joy and loyalty dogs bring to our lives—and the importance of showing them love in return.
Skyscraper Appreciation Day
Skyscraper Appreciation Day was established by Dr. Tom Stevens to celebrate the architectural and engineering marvels that define city skylines. The date marks the birthday of William Van Alen, architect of the iconic Chrysler Building in New York City. The observance invites people to admire the artistry, innovation, and cultural impact of skyscrapers—from early 20th-century masterpieces to today’s record-breaking towers.
Update Your Bio Day
Update Your Bio Day was launched in 2020 by Dr. Jason J. Jones as a lighthearted digital holiday encouraging people to refresh their online biographies. Chosen for its visual pun—8/10 resembling “BIO”—the day reminds professionals, creatives, and freelancers to keep their profiles current. As the pace of life and work evolves, the observance highlights the importance of staying visible and relevant in an online world.
World Lion Day
World Lion Day was founded in 2013 by Dereck and Beverly Joubert of the National Geographic Big Cat Initiative to raise awareness about the plight of lions. The day highlights threats such as habitat loss, human-wildlife conflict, and poaching, while promoting conservation efforts to protect these majestic animals. It also supports safety education for communities living near lion habitats. World Lion Day invites global admiration for lions as symbols of strength, beauty, and ecological importance.
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National Days in August
