I heard about the Christmas decorations in Diamond City when the in game calendar reaches Christmas day. I noticed a few days ago that my in game calendar was almost at Halloween, so I made sure to keep track of the days so I could visit Diamond City on Halloween. There's a banner across the entry stairway, some various pumpkin decorations on some of the buildings, and some plastic pumpkins placed around. There's also a cat that just hangs out right by the entry for the entire day, which you can see in the screenshots. There are a bunch of other cats wandering around the city as well. I kept finding them all over the place. They must have gotten out of Hawthorne's house. I was hoping to find some kids wearing Halloween costumes going trick or treating, but I didn't unfortunately.

I took some screenshots. If anyone wants to check them out they're on my Steam profile. There are a few other unrelated screenshots there. Mostly random teddy bear and skeleton easter eggs hidden throughout the game.

http://steamcommunity.com/id/quantumcurt/screenshots/?appid=377160

Side note - Can we upload images into threads here or is it disabled? I couldn't find a tool.

I still want to know why it doesn't snow on Christmas.

Presumably the nuclear fallout led to a big of global warming. That's been my assumption. Whether or not it's true is questionable, but it works for me.

Nah, it snows in FoNV. Where you meet Marcus, in that super mutant settlement.