is this recipe more summer than fall?

Agree with cv...your table, your guests, you choose what to serve.
But you seem a little worried.
Ask yourself what you like most about the dish...the meat, the sauce, the absolute reliability?
If you want to fiddle with any of these, practice (if there's time) before the dinner party with other options....e.g., a difference sauce more suitable for fall (red wine and shallot).
If you want to stay with this dish, do so and build your menu around it.

Wow that looks delicious!! I think it’s quite appropriate for fall. Might be fun to serve it with a roasted butternut or acorn squash salad.

I think it's fine for fall. Maybe just adjust what you serve with it - in summer, I might do a salad or two, in cooler weather maybe a hot rice or grain dish as well.

With all those peppers and the spiciness, I see this as a summer dish rather than fall. I back away from spicy dishes once cooler fall weather has arrived.

As fresh peppers are still available at my local farmers market, I don't see this as totally out of season yet.

Anyhow, it's really your call if you want to serve this to your guests.

sorry -- here's the recipe: https://food52.com/recipes/13451-beer-and-sriracha-marinated-beef-skewers-with-green-chile-sauce