There's still time to take part in the Shamrock Day seasonal event in Animal Crossing New Horizons if you hurry! Spring has officially returned to the northern hemisphere, and once you've downloaded the most recent update, you'll notice that a few changes have occurred on your island as a result of the new season. The most obvious change is that the snow has melted (and with it, your chances of catching dung beetles). 

Any snowmen you've constructed over the last few days, on the other hand, will remain in place and continue to melt at their normal rate. Furthermore, as Isabelle will inform you in her daily announcement, bamboo plants will now begin to produce the young spring bamboo crafting resource once more. In addition, you'll receive ACNH items in your in-game mailbox. The Mushroom mural wallpaper serves as a teaser for the Mario crossover items that will be released on March 1st in the game.
In addition to congratulating everyone on the return of spring, this update has introduced a couple of new minor holidays. Between now and Bunny Day (which this year will take place between March 28th and April 4th, coinciding with real-world Easter celebrations), you can commemorate three new occasions by purchasing items from Nook Shopping and the Able Sisters' tailor shop.

The Hinamatsuri Festival takes place from February 25th to March 3rd.
On March 3rd, the real-life Hinamatsuri Festival will take place in Tokyo, Japan. It is known in English as Girl's Day or Doll's Day, and it is traditionally observed by giving and displaying decorative dolls to young girls and young women. In the case of those who, like me, grew up with little knowledge of Japanese holidays, their only exposure to hinaningyo dolls may have come from the Fatal Frame series of horror games, which frequently incorporates them into creepy puzzles.
ACNH is now providing you with the opportunity to enjoy them in a less threatening environment. Nook Shopping app users can purchase two Hinamatsuri Festival-related items from the "Seasonal" section of the app's "Special Goods" tab, which is located under the "Seasonal" section. Additionally, in addition to purchasing your very own Hinaningyo doll display, you can also purchase a Blossom Lantern to use as a decoration for the festival.
Unlike most stores, you will not be able to purchase both items on the same day. Instead, they will be available for purchase through the app on alternate days, similar to how the seasonal display at Nook's Cranny operates. Between now and March 3rd, only one item will be made available per day. Therefore, if you want to ensure that you get both, you'll need to check back on multiple days.

Pi Day is celebrated on March 1st - 14th.
Okay, so calling this a real-world vacation is probably stretching the truth a little bit. Pi Day is celebrated on March 14th as a geeky joke because the date 3.14 represents the first three digits of the mathematical constant pi. When written in the British style (14/3), this does not work as well, but we are not going to argue about the relative merits of different date formats for the time being. The reason for this is that, in the absence of any deeply held traditions, it has become the accepted practice to celebrate Pi Day by eating delicious pie. And we appreciate any opportunity to indulge in some delectable cuisine.
This is the most straightforward addition to the new update. Beginning on March 1st (which also happens to be the day that the new Mario items become available in the game) and continuing until Pi Day itself on March 14th, you'll be able to purchase a  pie, also known as Pi Day Pie, in the game. It will be accessible from the Nook Shopping menu by selecting the 'Seasonal' tab.
From what we've seen so far, it appears that this will be purely decorative. Nonetheless, it will be a welcome addition to your kitchen, particularly if you are redecorating for the spring season. Keep it cooling near a windowsill for the most coziness possible. Is there anyone else who's hungry right now?

Shamrock Week is from March 10th to March 17th.
In addition to the new seasonal collections, the Shamrock Day set completes the line-up. Shamrock Day is, of course, a joking parody of the real-life celebrations of St. Patrick's Day in the United States. To include an in-game equivalent of what many people consider to be the true St. Patrick's Day main event (drinking green-dyed beer until you vomit), Animal Crossing would be a violation of the game's family-friendly nature. It is possible, however, to re-create the atmosphere of an overly-stereotypical Irish pub by purchasing a whole new set of clothes and animal crossing new horizons bells.
The Shamrock Rug, the Shamrock Doorplate (which reads fáilte!, which translates to "welcome! in Irish), and a Shamrock Soda are all new seasonal items available at Nook Shopping. Following in the footsteps of the Hinamatsuri Festival, only one Shamrock Day item will be available for purchase on the Nook Shopping app on a daily basis, continuing the trend started with the festival. That means you only have eight days to get all three items, so be sure to check back frequently if you want to get the entire collection.