I've read a lot about the New Weird "genre" in my explorations of the evolution of the "Weird Tale" at the end of the twentieth century, but at this point I'm mostly convinced that it isn't a clearly definable approach, style, aesthetic, or set of literary conventions. This isn't unique to the New Weird; generic definitions are almost always more about marketing than they are about descriptive utility. You might reach the same conclusion if you read:
Working Definition of New Weird (Jeff VanderMeer for the New Weird anthology)
What is the "New Weird" - and what makes weird fiction so relevant to our times? (Michael Moorcock, New Statesman)
The new world of New Weird (Damien G Walter, The Guardian)
New Weird (TV Tropes)
Cross-Crafting with a Vengeance: The New Weird (Karen Ostertag, New City Library)
Basically, all I've learned is that:
a) If a book is described as "New Weird" there's a better chance I'll enjoy it over books that are just described as "fantasy" or "science fiction."
b) M. John Harrison seems like a really grumpy guy.
My unpopular opinion: the "New Weird" started with Dune.
Anyway, what I'm most interested here is what media typically gets excluded from the umbrella of the New Weird. In contrast, the Gothic is a migrating genre--it started off as a descriptor for fiction, but it quickly adapted itself to stage drama, film, comics, etc. You get a little migration and adaptation with the New Weird; TV Tropes identifies some comics and tabletop games that seem within the bounds of its generic reach. But it's unusual to find film or television described as New Weird, which is interesting given the genre's supposed propensity to mash up disparate forms and mirror the transmedia state of modernity.
So I'll make a case for a something that is either a hidden precursor of New Weird or perhaps even an early example of the form:
Here's how it stacks up:Urban, secondary-world fiction that subverts the romanticized ideas about place (VanderMeer): The nations of Monica and Bregna are not of our world, or at least not recogniably of our world. And yet, the tension between the two is set-up as a space to explore modern anxieties without the romanticization of place found in fantasy fiction; while the two are analogs for fascism vs. freedom, both are irreducible to the category they supposedly represent. Both nations are urban and industrial (if not post-industrial).
It's a specific genre of Scifi/Fantasy/Horror literature that does not follow the conventions of derivative Sci-Fi, Fantasy or Horror, without being an outright parody or deconstruction (TV Tropes): Aeon Flux combines aspects of science fiction, pulp adventure, philosophic horror, cyberpunk, literary decadence, and fantasy, but the intention of the admixture is to avoid the derivative concepts of any of those genres. Although the show has elements of humor, parody, and deconstruction, those are coexisting elements rather than the point; the show is also serious, existential, and "academic" in its approach when the amusement wears thin.