It’s Oct. 25 this year, apparently. This guy tells us how to figure it out: It’s Durin’s Day! | Williamson County Public Library System Blog
As all should know.
Thank you for letting us know!
Now we can all go
I applaud that guy’s diligence in his no-prizing, but the simple fact is that Tolkien just wasn’t very good at his astronomy.
All of my sources on this say that it’s either November 22 or December 21, depending on whether you consider 12/21 to be in Autumn or Winter this year. (Winter begins on 12/21, but at about 6 PM Eastern time. In some parts of the world, it begins on 12/22, so Durin’s Day would be 12/21.)
I blame the damned elves with the moon runes and the dancing in the starlight and all the damn leaves. It’s always the elves.
And that depends on when “Winter” starts, which is not agreed upon.
wiki:" In one version of this definition, winter begins at the winter solstice and ends at the vernal equinox.[5] These dates are somewhat later than those used to define the beginning and end of the meteorological winter – usually considered to span the entirety of December, January, and February in the Northern Hemisphere … In the UK, meteorologists consider winter to be the three coldest months of December, January and February.[11]…In Scandinavia, winter in one tradition begins on 14 October and ends on the last day of February"
I’m not up on my Durins Day preparations. Time to start decking the halls with guts o’ goblins, I guess.
Elves.
:: shudder ::
Why’d it have to be Elves…?
Weathermen. Bah! I wouldn’t trust the word of one of them. What do they know? Bunch of frauds, the lot of them. Wouldn’t believe a weatherman if he told me my feet were wet while he was pissing on my boots.
Then you have D&D turning Elves into Fey.
Fey are really freaking scary.
Tolkein Elves as Fey would be horrifically nightmarish and you’d have to think Gandalf was completely fucking insane to take the fellowship anywhere near them.
All of this, of course, assumes that the Dwarves come up from their subterranean halls long enough to actually see the Moon and the Sun in the sky at the same time. One suspects that a wise-ass Wizard (or even a Hobbit) could come downstairs and tell the Dwarves that Durin’s Day was any day in particular, and they’d believe him. 
Filthy dwarrows. Everybody knows they’re basically Welshmen, even the girls. I’d no more celebrate Durin’s Day that I’d throw a life jacket to a drowning Prince Charles.
If you read the linked article, the author considers the Solstice to be the “middle of Winter”, not the “beginning (or threshold) of Winter”. In his view, the “threshold of Winter” is midway between the Autumnal Equinox and the Winter Solstice. That, combined with the lunar cycle, fixes the date to Oct 25 this year.
Nah, dwarves have to come up because grains don’t grow underground and without grain there’s no way to get beer or other alcohols necessary for dwarven life.
Mushroom beer.
Here’s a nice article on why we can’t figure out when Durin’s day was. Apparently even JRRT wrote a few different versions on how it was supposed to be figured out.
Plump helmets grow all year round.
Yeah, it’s not like the freakin’ Elves captured and imprisoned the LAST party he sent through their lands.
Oh, wait…