This is just a half guess, seeing as I have limited experience with molts, and even less experience with weather, but don't certain pressure systems usually bring rain? And Ts need higher humidity during a molt? So, maybe it's some sort of natural instinct, that help spurs the molting process. Maybe they have some sort of biologic clock that makes them more likely to molt during a wet season? I'm just speculating. If my wild guessing has any truth to it, I think these studies would be best done in a Ts natural habitat, becuase of the different weather patterns throughout the different parts of the world.