It opens pretty much when it gets cold enough. Sometimes it's open by now, but we haven't had any significant snow fall yet. Plus it's been really warm the past few nights. A good way to know is to check is to look at snow-valley.com They are the lowest resort, so if they are good and running then everything should be good. Oh... haha, their website says today is opening day. So there you go. However that's just the resort that has apparently been making snow. There won't be any laying around, so if you want to go tubing right now you'd have to pay. I'll let you know when there is snow laying enough to tube on.
And fyi, I'm not actually in big bear, I'm in crestline. I just say big bear becuase more people know where it is and crestline is a small town... don't want everyone knowing I live and grow here.