I have found no correlation between good visibility and anything else at all. Calm seas certainly don't hurt, but the worst visibility I have ever been in was with a 1-foot surf on the beach. There is however a very good correlation between bad visibility and storms, which is why a single hurricane can end the season.
Other factors which influence visibility are: algae blooms, spawning seasons of some invertebrates, which can fill the water with tiny swimmers, jellyfish ( yes, so many you can't see through them, luckily they don't sting, ) other divers churning up the bottom, and just plain gunk in the water. I don't know how to predict most of these, except to say that if you dive a lot, sooner or later you will see some good visibility. Sometimes in the ocean, the visibility will be different in different depth layers. I have seen the viz go from 3 ft on the way down the anchor line to 20 ft on the wreck.
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