Turkeys do go to open fields in the rain. Don't stay in bed or go home, but I think that they tend to fly down a little later in the a.m when it is raining. If there is no thunder, I think they also tend to be a little quieter on the roost if it is raining, so I try to have a good knowledge of their roost beforehand. I have a Doghouse blind I pack in when it is raining, set that up and sit in it. I stay nice and dry, even in downpours. One thing I learned, though, is that you need to get right to the field edge (or maybe set up in the field itself, like JW! says), not set back inside the woods 20 yards. And the turkeys won't necessarily favor a grassy strip alongside the woods over mud further out in the field. Seems they don't mind having a pound of mud on each foot. I think they tend to stay away from the edge because they lose some of their defense, hearing, with the rain, so they rely upon their vision more. I also think softer calling is more productive than loud yelping or cutting in the rain. As I think of it, I've never heard a hen cutt in rain, has anyone??

If there are no good fields, you need to find open clearings in the woods and set up.

Another thing, I've kicked non-nesting hens from pine stands/from under pine trees in the rain, (Easterns) and think there must be toms around somewhere, so I look for pines and clearings if I don't have a good field to work.

Finally, I only put out a single hen decoy, no jakes. (I have been tempted to put out 5-6 hen decoys and a passive jake in a field in the rain, as I often see small groups together in fields in rain and think that 6-7 decoys might better attract a lonely tom, but I haven't done that yet. Wet decoys don't look very natural to me, so I've always gone the 1 hen route.) I put the 1 hen 30 yards or so from my blind, and try to maximize her visibility, no around the corner or close to the edge tricks. I want any tom in the field to be able to see her, again because I think the birds are more visual and less hearing-dependent in the rain.