Most US sitcoms film in the summer. So that's irrelevant.
For instance, The Office generally ran from September to May. Filmed in the summer. Yet you constantly see episodes that are set in the winter, where people are bundled up, it's cold outside, etc. Because it's in Scranton, Pennsylvania. Even when it's irrelevant to the story line (Business Trip, Frame Toby, The Surplus, Scott's Tots, Prince Family Paper), they keep a consistent timeline of seasons.
Same with Seinfeld. It was filmed in LA, where it's never very cold, yet you constantly see everyone wearing coats and shit during the winter months because it's set in NYC.
And I think that's what made those two shows GOAT's. Seasonal realism is what the people want. It's what they crave.