Check this out. Pat knows what she is talking about.
Pats Big Ol' Mud Page (fixing muddy runs):
https://www.backyardchickens.com/web/viewblog.php?id=1642-fix-a-muddy-run
If they have been in the run for several weeks, they probably have an immunity to any Coccidiosis there, so it being wet probably does not put them at a tremendous risk. But definitely be on the watch for symptoms. It could become a problem.
Pats Big Ol' Mud Page (fixing muddy runs):
https://www.backyardchickens.com/web/viewblog.php?id=1642-fix-a-muddy-run
If they have been in the run for several weeks, they probably have an immunity to any Coccidiosis there, so it being wet probably does not put them at a tremendous risk. But definitely be on the watch for symptoms. It could become a problem.