Light Clothes, Miami
My SIL who lives in Miami will not wear any fabric but 100% cotton. I concur completely.
Do not wear any manmade blends e.g. a cotton t shirt that is just 5% lycra might as well be a plastic bag.
In the photo, Bob is standing (purple shirt) with a 100% cotton shirt, cotton shorts, cotton socks, and a hat which is pretty much ideal, although a lighter color shirt would be preferable especially in the summer. Khakis are lighter and more comfortable than denim.
Toiletries and Medical Supplies: Sunscreen