As mentioned before it rains a lot (see a theme here?) I take rain gear as a back up for the umbrella, but it can be hot though sometimes I get just as wet from sweating in the rain gear. But when the heavens open up and its raining so hard you can't see three feet it helps.
As far as what to wear that's an individual choice. Light, tightly woven cotton is the most comfortable, synthetics seem to feel hot and sticky. I have learned to stay with long pants and sleeves to keep the leeches off.
Leeches wait on leaves get on you as you walk by, they move like Slinky's up your boot or pant leg looking for a way to skin.... so everything is tucked in and buttoned! Some people even wear coveralls. Leech socks are also good to protect your feet and lower legs. They are usually a tightly woven cotton foot with a nylon upper which either ties or has elastic. Leeches can get down into your shoes and regular socks are no deterrent.
I wear gloves when handling bamboo it has fine hairs which will irritate your skin. They also protect from thorns.
I wear shorts around camp where I can keep an eye out for leeches. A wide brim hat can keep the sun off.