Unfortunately, it is not possible to get a reliable weather report or forecast for the Upper Keys, and especially Key Largo.
Forecasts come out of Miami or Key West, depending on how you do your forecast search. Usually, neither is accurate for Key Largo. We who live here have to figure it out for ourselves based upon the overall weather patterns.
The current readings from Homestead, only a half hour north of us by car, are often totally different from what is happening in Key Largo. Ditto for current conditions and forecasts for Key West.
What happens in Key Largo stays in Key Largo, and it is often a surprise, for better or worse.
But so far it sounds like an almost perfect weekend. The only thing that would make it better is to reverse the "forecast" and have the lighter air on Saturday and more air on Sunday. But at least it doesn't sound like it is going to be a blowout, as has happened with the Tradewinds several times (too much wind for most people to sail on one, or both, of the two days).
If the overall forecast holds, everybody will be able to sail both days.