What looks good (and I imagine feels good) is a long dress made of very light satin material. Looks smart if you want to go somewhere special (or just look special wherever you go), and is good at keeping the sun off.
Today is wet, cold and very blustery, and jeans and a fleece would be more appropriate. But this isn't normal!
Sorry - this assumes you're female. If you're male and want something other than shorts, long trousers/pants made out of a lightweight absorbent material (eg linen) would be good. But mostly just wear shorts. A golf shirt always looks smarter than a tee, and for the occasional cold evening bring a light sweatshirt. Don't forget a large baggy weatherproof top - the more tent-like the better. Often when it rains it's still very warm and humid so you want lots of ventilation.