I guess the question would be "how flooded?" I've seen plenty of birds fly down into a wet field (standing water covering most of it) but they usually make their way to the drier areas shortly after.
I've seen birds walk right through a swamp, and then seen others that avoid the water at all costs.
Not much of an answer for you, but I would say that if they walked through it to get to the roost it is probably not too wet for them. If they have moved roosting locations because of the flooded area, then you need to move to the birds.
Good luck out there, I still have to wait a month for season to open.

Andy, the worst of this weather should blow through before shooting light tomorrow, but it'll probably still be wet. Higher ground is probably a good strategy. I carry a lightweight camo poncho in weather like this--if you don't have one, try a military surplus store. I know a place in Ocala that sells them, but I haven't seen any good ones like the one I have in South Fla.

Hey Clay, the only open fields left in South Florida are baseball, football & soccer fields. All of the ag land has been converted to housing developments. OK, I exaggerate, but only a little--it's pretty much pavement from sea to shining swampland. LOL