I sail in Miami all the time. It's gotten warmer again
Long/short sleeved tops, knee-length pants, neoprene booties (there's spikey stuff in the bottom sometimes), all UV-blocking. Hats. Hats. Hats with wide brim. Hats with cover for the neck. Bandannas to cover the neck.
Loose fitting tops when it's very hot, tight-fitting when it's colder. Sometimes a light fleece on top.
When it gets cold (!) I wear a "spring" wetsuit. Even a wooly hat. Here's us with 70F/20C: https://www.youtube.com/watch?v=noreamEvKhE
All of the above I get as I find on sale; this being FL there's always UV clothing on sale somewhere
Weather forecasts are very reliable (windguru, windy.com). Rainy forecast most often means short-lived squalls, so you can sail anyway (mind lighting storms though).