Uncle John knows pretty much everything—and if he doesn’t, he puts one of his many researchers on the case. So go ahead: In the comments below, ask Uncle John anything. (And if we answer your question sometime, we’ll send you a free book!)

Why does the new TV season start in the fall?

The proliferation of cable networks and streaming services in recent years mean TV shows debut year-round now, but for the major broadcast networks—and over the last 50 years—new television programs debuted in September. (And new seasons of older showed resumed.)
It has a lot to do with the weather, and how that affects both the people who watch TV and the people who make it. Viewership levels drop in the summer because the weather is nice, the sun stays out until well into primetime, and so people are outside and having fun (or they’re seeing summer movies). But when fall hits, the weather gets chilly, the sun sets earlier, and people engage in indoor activities—like watching TV. New shows and new episodes of old shows show up right when this is happening.
But summer TV ratings are so low because the fare is mostly reruns. The people who make television want to be outside having fun, too. As the TV industry formed in the late 1940s, the big networks like NBC and CBS were offshoots of existing radio networks. The radio industry had been New York-based, and so the early TV industry was as well. During the summer, New York City happens to get very hot, very humid, and otherwise unbearable. The city’s wealthy traditionally retreat to summer homes in the Catskills or coastal New England. That group included radio executives and radio stars. So, the radio industry would shut down in the spring so its stars and creators could leave town. Radio in the summer was filled with reruns, and a similar thing happened when TV came along.