Thunderstorms and myself get along very well during turkey season. A lot of times turkeys will gobble at every clap of thunder, which lets you know they are still there. They will still work in the rain, but usually better during the lulls in the rain. Use a waterproof call, mouth call or keep your box call in a bread bag. Whoever tells you you ain't killing turkeys unless you are right is absolutely correct. Turkeys will generally head to fields during rain so make sure you are there. Also if you sit in the truck for the rain to stop and then head to the field, they will probably beat you. Rain gear or a good ponch will make the day friendlier. If you have apop up blind then that would be good to, I just don't use them. I always say about any type of hunting is,"animals don't go to a motel during bad weather, they are still out there!" By the way I have first season which starts tomorrow, I will be wet! And I am going to kill a turkey!
If you believe in the 150 pellets in the 10 inch circle, I guarantee you will miss more turkeys!!