Winter 2017 is different than just Winter. I did not say Winter started in January. I said Winter 2017 starts in January. Putting them together makes them different. It's like saying the 2016 season starts in April. 2016 starts in January, but the 2016 season starts in April. Kings Island is saying Winter 2017, not just Winter.
I see your point now, but most businesses and their managers (the ones you incorrectly imply nobody here knows anything about), when saying "Winter 2017" tend mean "the winter that starts in 2017".
Could it have been worded more clearly? Sure. I do think if they meant this coming winter, they would have said "this coming Winter". Also, if people are going to drop $100-200 on a pass (or anything, for that matter) and not fully know and understand what they're buying by not calling and asking questions, I'm not able to muster a ton of sympathy.