Nature Environment observances

Arbor Day

Last Friday in April; 24 April 2026 · United States-origin tree-planting and stewardship observance; National Arbor Day is the last Friday in April while state dates can differ by planting climate.

Arbor Day Foundation history verifies J. Sterling Morton’s January 4, 1872 proposal, the first Arbor Day on April 10, 1872, the 1874 Nebraska proclamation, the 1885 state-holiday stage and…

California Poppy Day

6 April annually · California, United States / state-designated educational observance

California Department of Education cites Education Code section 37222.12, which designates April 6 of each year as California Poppy Day.

Clean Up Australia Day

First Sunday in March · Australia-wide community environmental clean-up campaign

Clean Up Australia, official organizer

December solstice (Northern Hemisphere winter solstice)

21 December 2026 at 20:50 UT · Global astronomical December solstice / Northern Hemisphere winter-solstice naming; target-year instant is edition-specific

The U.S. Naval Observatory calculates the December 2026 solstice for December 21 at 20:50 Universal Time. USNO explains that solstices mark the beginning of summer and winter and that seaso…

Earth Day

22 April · Worldwide / EARTHDAY.ORG campaign

EARTHDAY.ORG’s current 2026 page identifies Earth Day 2026 as Wednesday, 22 April.

Endangered Species Day

Third Friday in May · United States conservation awareness observance

GovInfo records the U.S. Senate’s agreed S. Res. 431 designating May 11, 2006 as Endangered Species Day. Current U.S. Fish & Wildlife Service and Endangered Species Coalition material suppo…

Global Cat Day

16 October · Worldwide / Alley Cat Allies campaign

Alley Cat Allies identifies 16 October as Global Cat Day and describes it as its campaign centered on cats and communities.

Global Wind Day

15 June · international wind-energy awareness observance

GWEC states that it and WindEurope expanded earlier European Wind Day activity worldwide in 2009, changed the name to Global Wind Day, and continue the annual June 15 observance.

Greenery Day (Midori no Hi)

4 May · Japanese national holiday

Cabinet Office of Japan verifies Greenery Day as a national holiday, its 1989 creation on April 29 and the 2005 amendment moving it to May 4 from 2007.

Hagfish Day

Third Wednesday in October (21 October in 2026) · International / WhaleTimes ocean-education initiative

WhaleTimes states that it created Hagfish Day in 2009 and its own materials specify the third Wednesday of every October.

Houseplant Appreciation Day

10 January · Gardener’s Network-created informal houseplant appreciation observance

Gardener’s Network identifies itself as creator and sets 10 January each year; ASPCA safety material supports bounded pet-toxicity guidance.

International Animal Rights Day

10 December every year · Global animal-rights / animal-welfare advocacy observance

World Animal Protection states that International Animal Rights Day is observed on December 10 every year and is used to advocate for recognition and protection of animals as sentient being…

International Beaver Day

7 April · International / beaver conservation awareness

The Smithsonian’s National Zoo identifies 7 April as International Beaver Day, and a current municipal conservation notice also recognizes the date.

International Cat Day

8 August · Global cat-welfare awareness / International Cat Care

International Cat Care identifies International Cat Day on August 8 and describes itself as the custodian/coordinator of the day.

International Cheetah Day

4 December · international cheetah conservation awareness observance

Cheetah Conservation Fund (CCF)

International Clouded Leopard Day

4 August · International / clouded-leopard conservation awareness observance

The Aspinall Foundation records the first International Clouded Leopard Day at Howletts on 4 August 2018 and states that it was intended as an annual international awareness day; World Anim…

International Dawn Chorus Day

First Sunday in May; 3 May in 2026 · The Wildlife Trusts / international nature-listening participation

The Wildlife Trusts identifies International Dawn Chorus Day on the first Sunday in May and describes the celebration of birdsong at dawn

International Day for Biological Diversity

22 May · United Nations / Convention on Biological Diversity observance

A/RES/55/201

International Day for Biosphere Reserves

3 November · UNESCO international day

UNESCO General Conference observance

International Day for Preventing the Exploitation of the Environment in War and Armed Conflict

6 November · United Nations / international observance

A/RES/56/4

International Day for the Conservation of the Mangrove Ecosystem

26 July · UNESCO international day

Established by UNESCO in 2015

International Day for the Fight against Illegal, Unreported and Unregulated Fishing

5 June · United Nations / international observance

A/RES/72/72

International Day for the Preservation of the Ozone Layer

16 September · United Nations / international observance

A/RES/49/114

International Day of Action for Rivers

14 March · international river-protection and community-rights action observance

International Rivers states that participants at the first International Meeting of People Affected by Dams in Curitiba, Brazil, adopted the International Day of Action Against Dams and For…

International Day of Argania

10 May · United Nations / international observance

A/RES/75/262

International Day of Caves and Karst

13 September · UNESCO international day

International Day of Clean Air for Blue Skies

7 September · UNEP / United Nations / international observance

A/RES/74/212

International Day of Clean Energy

26 January · United Nations / international observance

A/RES/77/327

International Day of Combating Sand and Dust Storms

12 July · United Nations / international observance

A/RES/77/294

International Day of Forests

21 March · United Nations / FAO international observance

A/RES/67/200

International Day of Plant Health

12 May · United Nations / FAO international observance

A/RES/76/256

International Day of the Arabian Leopard

10 February · United Nations / international observance

A/RES/77/295

International Day of the Markhor

24 May · United Nations / international observance

A/RES/78/278

International Day of the Snow Leopard

23 October · United Nations / international observance

A/RES/79/143

International Day of the Tropics

29 June · United Nations / international observance

A/RES/70/267

International Day of Zero Waste

30 March · United Nations / international observance

A/RES/77/161

International Doodle Dog Day

1 May · International / creator-led doodle-dog community observance

The official International Doodle Dog Day site states that doodle dog lovers celebrate every year on May 1 and identifies Jeannie North as the founder.

International Environmental Education Day

26 January · International / environmental-education awareness observance recognized by education and biodiversity institutions

Environmental-education institutions mark January 26 as International/World Environmental Education Day. The evidence supports the recurring date but is not used to claim a current UN-desig…

International Geodiversity Day

6 October · UNESCO international day

Proclaimed by UNESCO General Conference in 2021

International Guide Dog Day

Last Wednesday in April each year · International guide-dog community / IGDF

The International Guide Dog Federation states that International Guide Dog Day is celebrated on the last Wednesday in April each year and raises awareness of guide-dog services and their ro…

International Mother Earth Day

22 April · United Nations international environmental observance

A/RES/63/278

International Mountain Day

11 December · United Nations international observance

A/RES/57/245

International Mud Day

29 June · international early-childhood nature-play observance

World Forum Foundation / Nature Action Collaborative for Children

International Orangutan Day

19 August each year · Orangutan conservation community / international awareness

Orangutan Foundation identifies International Orangutan Day on August 19 and uses the date for orangutan conservation awareness

International Plastic Bag Free Day

3 July · Environmental NGO campaign focused on reducing single-use plastic bags

Zero Waste Europe documents the International Plastic Bag Free Day campaign on July 3 and frames it around reducing lightweight plastic carrier-bag consumption and pollution.

International Polar Bear Day

27 February · Worldwide / Polar Bears International

Polar Bears International’s official event page identifies 27 February as International Polar Bear Day and describes the organization’s campaign around polar bear conservation.

International Rabbit Day

fourth Saturday of September; 26 September 2026 · International / rabbit welfare awareness

World Animal Protection describes International Rabbit Day as occurring on the fourth Saturday of September and gives 26 September for 2026.

International Red Panda Day

Third Saturday of September · International red-panda conservation education observance led by Red Panda Network; wildlife-welfare-safe and conservation-source-bounded

Red Panda Network first-party material states that it launched International Red Panda Day in 2010 and that the observance takes place every year on the third Saturday of September. Current…

International Respect for Chickens Day

4 May · International / United Poultry Concerns advocacy project

United Poultry Concerns identifies International Respect for Chickens Day as an annual May 4 project and traces the campaign to its 2005 launch.

International Sloth Day

Third Saturday in October · international sloth-awareness and conservation observance with a creator-side third-Saturday-in-October rule and a documented current October 20 usage variant

AIUNAU states that it created International Sloth Day as a commitment from the first international meeting on sloth wellbeing and conservation in Medellín in November 2010 and set it for th…

International Sunflower Guerrilla Gardening Day

1 May · International / guerrilla-gardening community observance

GuerrillaGardening.org documents International Sunflower Guerrilla Gardening Day on 1 May and says Brussels guerrilla gardeners declared it in 2007.

International Surfing Day

Third Saturday of June · Global surfing, beach-access and coastal-protection observance / Surfrider Foundation

Surfrider Foundation states that International Surfing Day began in 2005; its history records Surfrider Foundation and Surfing Magazine declaring June 20 International Surfing Day, while cu…

International Tiger Day / Global Tiger Day

29 July each year · Global tiger conservation awareness

WWF identifies Global Tiger Day, also widely called International Tiger Day, on 29 July as a day focused on tiger conservation awareness

International Whale Shark Day

30 August annually in current conservation usage · International / whale-shark conservation awareness

Wildlife Trust of India’s 2026 observance page states that International Whale Shark Day is marked every year on 30 August and documents its own continuing participation.

International Zebra Day

31 January in cited zoo and government sources · Wildlife awareness and zebra conservation observance

Smithsonian’s National Zoo uses 31 January for International Zebra Day, and a 2026 Taiwan government news service item likewise identifies 31 January and documents zoo programming around th…

IOSF World Otter Day

Last Wednesday in May annually · International / International Otter Survival Fund campaign

IOSF states that it established World Otter Day on the last Wednesday in May; its impact-report timeline records the launch in 2016.

Lake Superior Day

Third Sunday in July (19 July in 2026) · Lake Superior basin / binational U.S.–Canada environmental appreciation observance

The U.S. National Park Service and EPA Lake Superior management materials describe Lake Superior Day as an annual event on the third Sunday in July.

March equinox (Northern Hemisphere spring equinox)

20 March 2027 at 20:25 UT · Astronomical event / Northern Hemisphere seasonal naming; Southern Hemisphere is in autumn at the March equinox

The U.S. Naval Observatory Earth’s Seasons service gives the March 2027 equinox as 20 March 2027 at 20:25 UT and explains that equinox/solstice season names use the Northern Hemisphere conv…

March equinox / astronomical spring begins (Northern Hemisphere)

March equinox; 20 March 2026 at 14:46 UTC · March equinox instantaneous UTC event; Northern Hemisphere spring, Southern Hemisphere autumn; target-year calculation

The U.S. Naval Observatory publishes target-year equinox instants and explains that equinoxes mark the beginning of spring or autumn depending on hemisphere.

Marine Day (Umi no Hi)

Third Monday in July; 20 July 2026 · Japanese national holiday

Cabinet Office, Government of Japan

Marmot Day

2 February annually in Alaska · Alaska state-designated observance

Alaska legislation establishes 2 February of each year as Marmot Day and provides for suitable observance; Alaska State Archives also lists the day among state-designated dates.

Mountain Day (山の日)

11 August · Japan / statutory national holiday

Japan’s Act on National Holidays, as amended by Act No. 43 of 2014, establishes Mountain Day on 11 August and states its purpose as providing an opportunity to become familiar with mountain…

National Bird Day

5 January annually · Avian Welfare Coalition / captive-bird welfare and education campaign

The Avian Welfare Coalition says it established National Bird Day on January 5 as a day of action and education for captive birds; its anniversary material dates the campaign to 2002.

National Bison Day

first Saturday in November annually; 7 November 2026 · United States / bison recognition observance

NPS says National Bison Day has been observed annually on the first Saturday in November since 2012; WCS documents the Vote Bison Coalition’s inaugural 1 November 2012 celebration. Year-spe…

National Black Bear Day

First Saturday in June (6 June in 2026) · United States / National Black Bear Festival education initiative

The National Black Bear Festival states that it secured the National Black Bear Day designation and that the day is celebrated on the first Saturday in June each year.

National Black Cat Day

27 October annually · United Kingdom / Cats Protection annual adoption-awareness and animal-welfare campaign

Cats Protection states that National Black Cat Day is held each year on October 27, that it launched the first campaign on 27 October 2011 as Black Cat Awareness Day, and that it renamed th…

National Diatomaceous Earth Day

31 August · United States / EP Minerals-created diatomaceous-earth observance

EP Minerals states that it founded National Diatomaceous Earth Day, that National Day Calendar approved the day in 2016, and that the observance is on August 31.

National Feral Cat Day®

16 October annually · United States-origin / Alley Cat Allies community-cat advocacy campaign with international participation

Alley Cat Allies states that it created National Feral Cat Day® in 2001 for October 16. Its primary archives document the 2017 evolution to Global Cat Day® and current material treats Natio…

National Fossil Day

14 October 2026; annual date should be rechecked · United States — National Park Service paleontology education observance

National Park Service current National Fossil Day program

National Gardening Day

14 April · United States / widely recognized gardening observance with current USDA NIFA recognition

USDA’s National Institute of Food and Agriculture lists April 14 as National Gardening Day in its 2026 social-media toolkit.

National Hunting and Fishing Day

Fourth Saturday in September · United States — conservation and outdoor heritage observance

U.S. Fish & Wildlife Service states Congress established the observance in 1972 and it is celebrated on the fourth Saturday in September

National Love Your Pet Day

20 February · United States / pet appreciation observance with state-legislative recognition

New York Senate resolutions in multiple years identify February 20 as Love Your Pet Day in conjunction with the observation of National Love Your Pet Day.