The present observation of Greenery Day as a national holiday in Japan stems from the celebration of the Emperor Shōwa's birthday on April 29 every year during the Shōwa era. In 1989,  the name of the holiday was changed from "Birthday of the Emperor" to "Greenery Day".

Greenery Day - Japan

May Day is a public holiday usually celebrated on 1 May. It is an ancient Northern Hemisphere spring festival and a traditional spring holiday in many cultures. Dances, singing, and cake are usually part of the festivities.

May Day - UK

During the “cultural revolution” May Day in China was considered, almost the most important holiday in the country. Amplitudinous rallies and demonstrations across China were organized to celebrate this Day. The holiday was more of a political character.

May Day - China

International Workers' Day, also known as Workers' Day, Labour Day in some countries and often referred to as May Day, is a celebration of labourers and the working classes that is promoted by the international labour movement which occurs every year on May Day, an ancient European spring festival.

International Workers' Day

May Day, or the Early May Bank holiday, is on the first Monday of May each year.

Early May Bank Holiday

Labour Day holiday for Queensland, Australia.

Labour Day - Queensland

Labour Day is an annual holiday to celebrate the achievements of workers. Labour Day has its origins in the labour union movement, specifically the eight-hour day movement, which advocated eight hours for work, eight hours for recreation, and eight hours for rest.

Labour Day

For many Russians, Spring and Labor Day, which falls on May 1, is a family holiday and a time for relaxation.

Spring and Labor Day

May Day in Germany is a holiday to celebrate the start of spring and to campaign for workers' rights. It is always on May 1.

May Day

Labor and Solidarity Day, which falls on May 1 each year, is one of the most controversial holidays in Turkey. 

Labor and Solidarity Day

Day of the Flag

Full Moon Day of Kasong is a national public holiday in Myanmar. It is also known as “Buddha Day” because it commemorates the birth, enlightenment, and nirvana (death) of Buddha, all of which are believed to have occurred on the same day of the year.

Full Moon day of Kasong - Myanmar

Constitution Memorial Day is a national holiday in Japan. It takes place on May 3 in celebration of the promulgation of the 1947 Constitution of Japan. It is a part of the collection of holidays known as Golden Week.

Constitution Memorial Day - Japan

Constitution Day is an annual public holiday in Poland on May 3.

Constitution Day

The United Nations General Assembly declared May 3 to be World Press Freedom Day or just World Press Day to raise awareness of the importance of freedom of the press and remind governments of their duty to respect and uphold the right to freedom of expression.

World Press Freedom Day

Youth Day is a holiday dedicated to the youths of a country. It is observed by 18 countries, on many dates throughout the year.

Youth Day  - China

Star Wars Day, May 4, celebrates George Lucas' Star Wars. It is observed by fans of the media franchise.

Star Wars Day

International Children's Day is a day recognized to celebrate children. The day is celebrated on various dates in different countries to promote children's welfare, children's rights and ultimately to build a better environment for all children of the world.

Children's Day

Wesak is a day celebrated by Buddhists around the world. The term Wesak comes from the name of a month in the Indian calendar.

Wesak Day

Children's Day is a Japanese national holiday which takes place annually on May 5 and is the final celebration in Golden Week. It is a day set aside to respect children's personalities and to celebrate their happiness. It was designated a national holiday by the Japanese government in 1948.

Children’s Day - Japan

Cinco de Mayo is an annual celebration held on May 5. The date is observed to commemorate the Mexican Army's victory over the French Empire at the Battle of Puebla, on May 5, 1862, under the leadership of General Ignacio Zaragoza.

Cinco de Mayo

Pahang State Holiday (Pahang)

Mother’s Day is celebrated in Poland on May 26 each year. 

Mothers' Day

WWII Victory Day marks the anniversary of the official end of World War II and is a public holiday in France.

WWII Victory Day

Parents' Day

Victory in Europe Day, generally known as VE Day (Great Britain) or V-E Day (North America), is a day celebrating the formal acceptance by the Allies of World War II of Nazi Germany's unconditional surrender of its armed forces on the 8 May 1945.

Victory in Europe Day - USA

World Ovarian Cancer Day aims to create a community where those living with ovarian cancer, survivors and their families and friends can unite, share their experiences.

World Ovarian Cancer Day

'Pahang State Holiday' observed (Pahang)

Lag BaOmer, also Lag B'Omer, is a Jewish holiday celebrated on the 33rd day of the Counting of the Omer, which occurs on the 18th day of the Hebrew month of Iyar.

Lag BaOmer - Jewish

End of World War II

Lost Sock Memorial Day on May 9 is a day to commemorate lost socks. The unofficial holiday also encourages people to let go of all the remaining single socks they are collecting in hopes of finding their partners one day.

Lost Sock Memorial Day

Europe Day is the name of two annual observance days, 5 May by the Council of Europe and 9 May by the European Union. The first recognition of Europe Day was by the Council of Europe, introduced in 1964.

Europe Day -  EU

National Public Gardens Day, occurring annually on the Friday before Mother's Day, is a day to promote awareness of botanic gardens, arboreta, zoos, historic gardens, or any of North America's public gardens.

Public Gardens Day

International Nurses Day (IND) is an international day observed around the world on 12 May of each year, to mark the contributions that nurses make to society.

International Nurse Day

Mother's Day is a celebration honoring the mother of the family, as well as motherhood, maternal bonds, and the influence of mothers in society. It is celebrated on various days in many parts of the world, most commonly in the months of March or May.

Mothers Day

Mother's Day

Teacher's Day

The International Day of Families is observed on the 15th of May every year. The Day was proclaimed by the UN General Assembly in 1993 with resolution A/RES/47/237 and reflects the importance the international community attaches to families.

International Day of Famiies

The celebration of this day expresses the desire for peace of persons of all religions, as well as non-believers.

International Day of Living Together in Peace

Norwegian Constitution Day is the national day of Norway and is an official public holiday observed on May 17 each year. Among Norwegians, the day is referred to simply as syttende mai, Nasjonaldagen or Grunnlovsdagen, although the latter is less frequent.

Constitution Day - Norway

Ascension Day marks the day that Jesus ascended to heaven following his crucifixion and resurrection, according to Christian belief. It is the 40th day of Easter and is ten days before Pentecost Sunday. It is a public holiday in France.

Ascension Day

Yom Yerushalayim, also known as Jerusalem Day, commemorates Jerusalem's reunification in 1967. This day begins on 28th day of the month of Iyyar in the Hebrew calendar.

Yom Yerushalayim - Jewish

Father's Day is a celebration honoring fathers and celebrating fatherhood, paternal bonds and the influence of fathers in society. In Catholic countries of Europe, it has been celebrated on March 19 (Saint Joseph's Day) since the Middle Ages.

Father's Day

Ascension Day in Germany is on a Thursday 39 days after Easter Sunday.

International Museum Day (IMD) is an international day a celebration that held every year on or around 18 May, coordinated by the International Council of Museums (ICOM).

International Museum Day

Many people in Turkey annually observe the Commemoration of Atatürk, Youth and Sports Day on May 19 by attending sports events and remembering Turkey’s War of Independence, which started on this day in 1919.

Commemoration of Atatürk, Youth and Sports Day

This event historically unites thousands of people in 60+ countries worldwide to DRIVE global awareness and education about the AUTOimmune and AUTOinflammatory diseases that include inflammatory-driven arthritis (AiArthritis)

World Autoimmune / Autoinflammatory Arthritis Day

Europe Day is observed in Ukraine on the third weekend in May.

Europe Day

The International Day for Biological Diversity is a United Nations–sanctioned international day for the promotion of biodiversity issues. It is currently held on May 22.

International Day for Biological Diversity

Victoria Day is a federal Canadian public holiday celebrated on the last Monday preceding May 25, in honour of Queen Victoria's birthday. As such, it is the Monday between the 18th to the 24th inclusive, and thus is always the penultimate Monday of May.

Victoria Day - Canada

Marked annually on May 24, National Scavenger Hunt Day is set aside as a day to enjoy the good ol’ fashioned fun of a scavenger hunt.

National Scavenger Hunt Day

May 25 is African Liberation Day. On this day, many African countries celebrate the hard-fought achievement of their freedom from European colonial powers.

African Liberation Day

Shavuot, in Ashkenazi usage, Shavuʿoth in Sephardi and Mizrahi Hebrew, is known as the Feast of Weeks in English and as Pentecost in Ancient Greek. It is a Jewish holiday that occurs on the sixth day of the Hebrew month of Sivan, meaning it may fall May 15 – June 14.

Shavuot - Jewish

The May Revolution was a week-long series of events that took place from May 18 to 25, 1810, in Buenos Aires. This Spanish colony included roughly the territories of present-day Argentina, Bolivia, Paraguay, Uruguay, and parts of Brazil.

Revolution Day - Argentina

Independence Day is a national holiday that is celebrated on May 25 which commemorates the Jordanian Parliament's ratification of the Treaty of London on 25 May 1946.

Independence Day - Jordan

Buddha's Birthday

Independence Day is an annual public holiday in Georgia observed on 26 May. It commemorates the 26 May 1918 adoption of the Act of Independence, which established the Democratic Republic of Georgia in the aftermath of the Russian Revolution of 1917. It is the national day of Georgia.

Independence Day - Georgia

Buddha's birthday is a holiday traditionally celebrated in most of East Asia to commemorate the birth of the Prince Siddhartha Gautama, later the Gautama Buddha and founder of Buddhism. It is also celebrated as Vesak which also acknowledges the enlightenment and death of the Buddha.

Buddha’s Birthday

Pentecost Sunday is 50 days after Easter Sunday. It marks the Holy Spirit's descent onto Jesus' followers, according to Christian belief.  

Whit Sunday

Ethiopia’s national day comes every 28 May and is referred to as Derg Downfall Day. It commemorates the defeat of the tyrannical, Communist Derg military regime by forces that resisted it for many years during prolonged civil war.

Derg Downfall Day - Ethiopia

Kiev Day is observed in Ukraine’s capital city, Kiev (or Kyiv), on the last weekend in May. 

Kiev Day

National Hamburger Day is an unofficial holiday variously observed on May 28, July 28, and December 21. It's an occasion to celebrate hamburgers, primarily in the form of eating them.

National Hamburger Day

Pentecost is a Christian holiday to remember the Holy Spirit's descent onto Jesus' followers.

Whit Sunday (Most regions)

Whit Monday, is the day after Pentecost. Many Christians believe that on Pentecost, the Holy Spirit descended on Jesus Christ's disciples. Pentecost Monday was a public holiday in France until 2005 and again from 2008.

Whit Monday

The spring bank holiday in the United Kingdom is on the last Monday of May each year.

Spring Bank Holiday

Reconciliation Day is a public holiday in the Australian Capital Territory marking the start of National Reconciliation Week. It is held on the first Monday after or on 27 May, the anniversary of the 1967 referendum. It was held for the first time on 28 May 2018.

Reconciliation Day - Australia

The Second Day of Pentecost is, which is on the Monday after Pentecost (or Whitsunday), is a public holiday in Germany.

Memorial Day  is a federal holiday in the United States for remembering and honoring the military personnel who died while serving in the United States Armed Forces. The holiday is observed on the last Monday of May. Memorial Day was observed on May 30 from 1868 to 1970.

Memorial Day

Harvest Festival (Labuan, Sabah)

Loomis Day is observed annually across the nation on May 30. Washington, DC dentist, Mahlon Loomis, received US patent number 129,971 titled “An Improvement in Telegraphing”.

Loomis Day

World No Tobacco Day (WNTD) is observed around the world every year on 31 May. It is intended to encourage a 24-hour period of abstinence from all forms of tobacco consumption around the globe.