This year Therianthropy Day falls on November 23. Therianthropy Day falls on the day of the first November full moon, so it moves. It’s on a different day each year. Last year (2017) Therianthropy Day was on November the 4th, which happened to be the same day that the first howl was held in 1994.
November 7, 1993 is the day that a bat-identified person began to talk about his dreams of being a bat and feeling like a bat on the Usenet group Alt.horror.werewolves. That discussion is considered a starting point for Modern Therianthropy and the online community. The group Alt.horror.werewolves was created a year earlier on November 16, 1992. So, November is a significant month to us historically.
Werebat dreams - https://groups.google.com/forum/?fromgroups=#!topic/alt.horror.werewolves/cnaZs0KC9Bk
More info about the first Howls - https://therian.wikia.com/wiki/Howl
Also, the idea of a day like this for Therianthropes is not new.
“It was first proposed as a sort of holiday in March of 1996. Ultimately, AHWW decided to use it, and it stuck. It went through a few iterations of names, “International Werewolf Day”, and then the less species-specific “Awereness Day” (since were is the older term for therian), and after the term therianthropy caught on, “Therianthropy Day”.”
Here’s a link to the 1996 “International Werewolf Day” discussion on AHWW. https://groups.google.com/forum/?fromgroups=#!msg/alt.horror.werewolves/eOvzhlG3IaI/NqmIpx9-JN4J;context-place=forum/alt.horror.werewolves
Therianthropy Day is meant to encourage the acknowledgement of our history and the spread of accurate information. This is a day to recognize the Greymuzzles from AHWW who founded and built up the online community. Many support this day in the hopes that it can synchronize the online community and bring it together despite it being spread out across various social media platforms. Therianthropy Day is also supported by many who feel that Therianthropes need to form some solid traditions to strengthen our culture.
Along with the emphasis on history, the day is meant to be fun and lighthearted. Building connections and relationships with other Therianthropes is a large part of Therianthropy Day since it commemorates the first Howl. This can be done through chatting, playing games, and meeting up with others in real life if possible. Therianthropes are also encouraged to take part of this day for self-care.
Unfortunately, there is some opposition to Therianthropy Day. Some feel that it too closely resembles "Pride" celebrated by LGTBQ+ peoples. In response to that, an effort has been made in the online community to educate the younger Therians who want "Therian Pride" and explain to them that calling for "Therian Pride" is inappropriate. Others oppose Therianthropy Day because they think it only encourages "fluff" and roleplay.