I'm no bio, so take it for what it's worth. From what I've been seeing is that the hens weren't ready for breeding earlier, they are just now starting. Other years most hens were nesting already, and this year they've been late. Toms have been strutting since mid March, but the hens didn't want anything to do with them. All season I'd see toms with toms and hens by themselves, and if a tom would get near a hen she'd run off. You could call to the toms and they wouldn't give you the time of day, not all, but most. These last two weeks the hen have been going to the toms and your calling has gotten a lot more responces. I had a tom come in Weds and then three hens entered the field and that tom headed over by them and they all ran off. Everything seems to be a bit later this year?
To answer your question, yes heavy rains will effect nesting depending on where the nest is, and these last couple storms we've had has had some large hail with them, if a nest is uncovered I'm wondering how much the hail danages a nest? Today there were 6 toms in the field and each tom had about 5/6 hens with him all at the same time, right after the storm passed.