One thing that kept me coming back to BGW during the off season was the passholder perks. I feel like these events should be geared around passholders. The Busch bucks, free Quick Queues per visit and the extras like the food booths, shows and the Darkoaster preview center made it worth going to BGW even in February. IDK why CF didn't bother doing stuff like that.
SFOT had a cool off season event running in January to draw people in. They kept the Christmas lights up and had fire and ice displays everywhere. Of course the weather down there is a bit more mild in winter but they were still pulling a decent crowd in the middle of January because they had a festival running.
If these parks wanted to turn a profit in winter, give people a reason to come back. Passholder perks are an easy way to do that. You're not gonna pull people on vacation in January-March. Passholders looking to leave the house are gonna make up the bulk of your visitors,
CGA going seasonal is kinda shocking too considering the weather in NorCal is really mild and SFDK seems to operate year round. More money to them I suppose.