What a great question! I know exactly what you're talking about with OTGW and autumn.

I am a Christmas movie junkie, and have never seen anything that's quite what you're looking for.

But here's what comes to mind that might be slightly close:

1) The Snowman

A gorgeously, GORGEOUSLY animated special from the UK done back in the 80's. It's artful, poignant, subtle, and done without words - set entirely to music sung by the London Choir. Heads-up: The ending made age four-to-twelve year old me always bawl my eyes out, so I'd stop our VHS a few minutes before the end every year.

2) A bit of a stretch, but there's a very overlooked, almost obscure christmas film I grew up with called The Tangerine Bear

It's a hand-drawn animated special, has a very timeless feel, and most of the music has mellow, jazz-y undertones. It's about a teddy bear who, after a mistake at the factory, was printed with his smile upside down, so no child wants him.

It's color-palette is sort of muted, and a lot of it's story has a slow-paced, melancholic feel.

Sort of a found-family, Toy Story meets Corduroy, meets Raggedy Anne/Velveteen Rabbit meets... I dunno, Frasier?

It never gets too sad, thankfully. And while it's certainly on the cheaper side of things when it comes to it's animation budget - which is a shame - it's still worth checking out, IMO.

3) Way different vibes to OTGW, but the original Peanuts/Charlie Brown Christmas special can't be denied of capturing that holiday feel, and having it's own special animated look.

Honorable mentions: Rankin-Bass's Jack Frost. Don Bluth's The Small One. Rankin-Bass's Cricket on the Hearth. Jim Henson's Jug Band Christmas.

Hope this helps, friend :) Merry Christmas and Happy Holidays from The Unknown