I love hunting in the rain. Once the weather breaks, the hunting can be outstanding. Some of my best hunts have been between rain showers. The best is when the rain lets up and there is thunder in the distance. Every gobbler on the property will be gobbling.
Screw the gound blind (waaay too boring). I throw on my rain suit, grab a mouthcall and a waterproof slate call and striker and take off.
You can count on the birds being in fields. Rain limits their vision and hearing so they seek open ground. Also, the rain stuns insects and makes it easier for them to catch. However, if it is a pretty serious storm, they will hunker down under some type of cover until the storm passes. But as soon as the storm passes, they will hit the fields to dry off.
If I know turkeys go to a certain field when it rains, I'll setup close enough to the edge of the field to get a shot but far enough back that I can slip out of there without the turkeys seeing me. This is important b/c sometimes during rain showers the turkeys won't move much. If this appears to be the situation, I'll use the rain to my advantage and try to sneak within gun range.
Rain is a turkey hunter's best friend. It keeps a lot of public land hunters at home, makes the turkeys more predictable, and puts the odds more in your favor by limiting their vision and hearing.