The end of summer has a distinct mood and that bittersweet vibe never leaves you, even when you’re an adult and, tragically, not on a schedule with a summer vacation. Even though we have months of warm weather and months until a new year, is there any season that really makes you feel the passage of time more than this one? I have been thinking about films that capture this pleasantly sad frame of mind.

Summer’s pleasures are no doubt heightened by their fleeting nature, and summer romance even more so. “Call Me By Your Name” must be one of the most memorable onscreen summer romances, and the end of the film’s romance is as important as its simmering beginning. Teenaged Elio and Oliver, his father’s graduate student assistant, were never meant to last, for a variety of reasons, but their short-lived relationship leads Elio’s father to deliver a lengthy meditation on not just their relationship, but on the transitory nature of, well, pretty much everything.

This film is celebrated for its sumptuous cinematography, frank sensuality, peaches, short shorts and the father’s incredible monologue, delivered by Michael Stuhlbarg, which is deeply moving and full of personal and universal revelations. “Call Me By Your Name” is an instant summer classic, but also ends as each year ends, with winter. Elio’s emotions quietly spill over in the film’s beautiful final moments, capping off Timothee Chalamet’s rightly celebrated performance.

The likable coming-of-age comedy “The Way, Way Back” also features summer as a stand-in for childhood, and fall as a metaphor for growing up. The main character, a teenage boy named Duncan, even works at that most seasonal entity of all, a water park. Here, the awkward boy who is struggling under the thumb of his mom’s overbearing boyfriend makes friends, gains confidence and meets an appealing father figure in his childish boss, Sam Rockwell.

“American Graffiti” is a film that was already about nostalgia when it was made, and is now 45 years old. Since nostalgia is the unofficial emotion of fall, this film fits the bill for capturing our bittersweet September mood. On the last night of summer vacation in 1962, teenagers drive around town in a variety of memorable cars, thinking about what growing up means to their lives as they are now. Since it’s September, change is in the air and “American Graffiti” captures that perfectly.

It was actually a TV show, not a movie, that put me in this whole September mind frame. The incomparable cartoon “Gravity Falls” takes place over a single summer and conflates the end of summer with the end, not just of childhood, but of the entire world. The 12-year-old twins, who have spent a summer in the Pacific Northwest solving mysteries with their great-uncle Stan, unleash an apocalyptic menace on the universe as we know it, rather than turn 13 and leave Gravity Falls.

Let me take this opportunity to advise you to check out “Gravity Falls” if you have kids and desire a show that will entertain you as well, as this witty and exciting Disney cartoon is like “The X-Files” for kids. Or it was, I should say, since, in keeping with our theme, this gem was short-lived … just like summer.