Two that I just watched that felt pretty summer-y: X and Pearl.

And some others that are not necessarily the best, but are on fall and winter movie lists of mine:

Fall: Sleepy Hollow, Jeppers Creepers, An American Werewolf in London, Candyman, Fright Night

Winter: Snowpiercer, Gremlins, The Wolf of Snow Hollow, The Thing, Black Christmas

Can't believe I forgot the other quintessential summer horror movie: Texas Chainsaw Massacre

I spent July 4 rewatching I Know What You Did Last Summer. It just seemed appropriate. Wish I'd thought about Midsommar. That's a great movie.

Summer: I guess anything that takes place at camp: Friday the 13th, The Burning, Sleepaway Camp, etc.

Fall: Halloween, obviously.

Winter: The Shining. More recently I liked The Lodge. Frozen was good too.

Spring: Hmm...not sure about this. April Fool's Day is the first movie off the top of my head that definitely takes place in spring. What else signifies spring? Easter? Spring Break?

Satan's Little Helper is the best movie for Halloween.