Being born and raised in Key West - my boys have always enjoyed going snorkeling - I believe they have snorkeled all up and down the keys and in all kinds of weather and in every month of the year - I have seen very few bad days in Key West, but of course like any thing else - it is prone to changing - when are you planning to go to Key West - the waters in and around Key West is just so beautiful but unfortunalty due to the way that those that come to visit Key West, do not have respect for the coral reefs or for that fact the ocean or the gulf and we are losing the beauty it once was - I remember walking all around Key West and there wasn't one place you couldn't see the waters and most of all it was healthy - you are most welcomed to send for the Key West informative packages I offer those going to Key West - they do not cost anything except for the cost of a large manilla envelope and $3.75 in postage - also make it self addressed.
Anyhow hope you enjoy my hometown when you go there - you should have seen Key West during my times - now that was a Magical paradise.
Always
Shirley