After a storm the water gets milky for a few days until the limestone settles out again.
Isaac will be gone by then but this time of year there could always be another TS.
Yes the viz may be less but for me coming down from NJ 15’ would be fine and it’s warm :) It depends on what you like and what you are looking for. I remember a trip to Bonaire, they had a storm and viz had dropped to 50’ and they didn’t want us to dive!