The Almanac is just full of educated guesses.
I'm 50/50 with it. Sometimes it's been dead on the money and other times??? Not so good. I just take whatever comes my way.
We are supposed to have a cold winter, at least in my area anyway, but that's because we are coming out of an "El Nino" weather cycle and going into a "La Nina" (you can read more about that with this link).
I do believe that people picked up on weather patterns over time without knowing that it is something science, as well as a person who has lived long enough to see it happen over and over, can predict fairly accurately.
Sure there are a lot of variables involved. Over the years it has been either right on the nose or close to it enough times for me to pay attention to it. Like years ending in an odd number seem to be better years for me all around.