Was originally curious about summer specific horror movies but realized there was no reason to limit the discussion. For my example I have yet to see a movie that even comes close to Midsommar in terms of summer-y vibes.
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?