Deleted

Here is one off the top of my head from Endless Legend. https://www.trueachievements.com/a299725/endless-day-achievement

https://astats.astats.nl/astats/TopListAchievements.php?DisplayType=UpcomingAchievementMoments

The best I can find so far

The first Dreadout has one for playing on a certain day of the week. Thursday, I think.

Each Halo in MCC has one I believe

all the ones ive run into you could just change the clock on your pc
been abusing animal crossing time travel for YEARS

I know that the Stanley Parable has one where you need to not play for 5 years. But I don't think that's what you're looking for.

In Terraria there are achievements for doing things in certain times of the year, Christmas, Halloween.

Psychonauts. A hidden achievement called "Christmas Shopping" that can only be collected on Christmas Day.

Iirc one way to die require you to open the game both on christmas and halloween to get the themed event on.

https://steamcommunity.com/stats/752300/achievements
Forestation has a Secret Santa Is Watching You achieve - Visit the game between December 31 and January 3.

https://steamcommunity.com/stats/286360/achievements
Shadows on the Vatican Act I: Greed has a Ho ho ho! achieve - Try entering from the chimney on December 24th

https://steamcommunity.com/stats/269050/achievements
Year Walk has an achievement for playing the game on New Year's eve called New Year.

https://steamcommunity.com/stats/CostumeQuest/achievements
Costume Quest has an achievement for playing the game on Christmas called Tisn't the Season.

https://steamcommunity.com/stats/1250870/achievements
Cyrano Story has and achievement for playing the game on Halloween called Halloween and another called Time Capsule for playing the game in... 2063.

Journey of a Roach has an achievement for playing between Nov 4 - 30 and collecting all of the pieces of cake.

https://steamcommunity.com/stats/1172530/achievements

Daylife in Japan has one to play between 3 and 4 am

https://www.achievementstats.com/index.php?action=calendar&year=2021&month=2
https://www.achievementstats.com/index.php?action=achievements&mode=seasonal

Adding to other mentioned games - Dirt 4 has an achievement where you have to destroy a car on monday
https://www.trueachievements.com/a235334/mondays-be-like-achievement

I came across several but I just remember this one.. So boring xd

=> Play The Stanley Parable for the entire duration of a Tuesday.

Jackbox Party Pack 7 for playing one of the games on a Friday night.

https://steamcommunity.com/stats/895620/achievements
Spellcaster University - Return of the druids - play the game on the day of the Beltane festival (1st May)

SUPERHOT - Launch pumpkin spiced challenge between 24.10 & 7.11
https://truesteamachievements.com/a191342/pumpkin-spiced-superhot-achievement

Collisions - They added some date-specific achievements in a patch. Rather annoying in my opinion, particularly if the game was previously "completed"

Edit: There is one that only occurs every four years but they also added an in-game way of "cheating" the time for these achievements so they seem rather pointless from that perspective.

I asked that once and i believe someone posted an astats link for me then.

[EDIT] http://astats.astats.nl/astats/TopListAchievements.php?DisplayType=UpcomingAchievementMoments

Played quite a big of Northgard last month and there's an achievement that pops up only if you make a snowman on a special event near Xmas
Do you want to build a snowman?

I played another game recently that had an achievement you could only get on a specific date (you could change your PC date and time to get it though) but I can't remember what it was. I'm going to look it up

Coffin Dodgers has achievements that have to be done on Halloween, Christmas and Valentine's
https://store.steampowered.com/app/320540/Coffin_Dodgers/
https://steamcommunity.com/stats/320540/achievements