Three Seasons Only

''There's spring, summer, and fall. I disown winter!''

No. Not those seasons. There Are Only Three Seasons refers to the first few seasons of a show being good while later ones are, at most, moderate. This is a sign that a TV show or series is, if it hasn't already, in the process of losing its magic. It may still have some of its former glory lingering around in the episodes, but the episodes are still mostly Too Boring To Survive. If the creator is smart enough, they'll go with the hard-yet-dignified option of Canceling The Whole Thing instead of being around for much longer than anyone is willing for them to.