It depends on the DZ. Some places will send everyone home, some will have the staff stay, hoping it will improve. It also depends on the forecast.
I've heard it said that there's a 100% chance you won't jump if you aren't at the DZ.
I've spent a lot of time sitting around waiting. Sometimes it gets better and I've gotten to jump, other times we've just sat around.
That doesn't mean that time can't be constructive.
I've seen:
A USPA Board member and Tandem I/E grab the TIs and spend most of an hour going over Tandem EPs.
The S&TA and head instructor grab all the students, along with recent A license grads and sit around going over everything. One thing he repeated was "is there anything you need or want a better understanding of?"
A rigger go over gear with anyone who was interested (students and experienced jumpers). Same basic 'is there anything you want to know about?'
The pilot sitting and answering questions about the plane, flying, all that (not everything was jump related, but it was still informative).
There's also the opportunity to become part of the community. The DZO has said that anyone who makes their first AFF jump is part of the group and welcome to join in the 'non-jumping' activities (cookouts, parties, bonfires, ect).
If you plan on continuing jumping, you will need friends to jump with. Hanging out with those people and getting to know them (and letting them get to know you) is important for that.
Besides, in addition to the 'instructive' stuff, I've also seen throwing knives, a bull whip, balance rollers, BMX bikes, creeper bowling and a few other things I can't think of right now. Most were being used by people who had some skill, most were offered for anyone who wanted to try.
We get a bit silly sometimes.