Ugh - I hate to even think about this! We are going Oct 21-27. I'm counting on a turnaround of the forecast!! Although one good thing...my parents took us to WDW in October as kids and it rained every. single. day. Place cleared out and there were no lines!! I realize its a different time and that won't happen as much, but it may help.
As for your question, I think all outdoor rides will shut down if there is lightning. I've also heard Test Track shuts down if its raining, no lightning required.