It’s official (according to Vulture, at least): Katy Perry’s “California Gurls” was 2010’s song of the summer. Now that that’s decided, we’re kind of hoping we’ll never have to hear it again. Thankfully, we’re entering what may be our favorite time of year for music. In early September, when it’s still fairly warm (or, like New York today, insufferably hot) but the first signs of autumn are beginning to show, we tend to like our music a bit less intense than the pop jams we blasted June through August. As the days grow shorter, even us city dwellers feel like returning to organic sounds — atmospheric stuff, whispery indie-pop, or even just earthy guitar rock. With that in mind, we’ve created our perfect mixtape of songs about and that evoke the feel of this transitional time of year. Side A: Late Summer; Side B: Early Fall.