It gets really hot and humid and rains quite a bit here, too, so I'll share my tricks. The only part of my bike I mind being wet is the seat, so I carry an extra plastic grocery bag or two to put over my seat, and then close it with a twist tie around the seatpost. I wear a yellow poncho in the winter when it rains, with a sweater underneath. In the summer, with the heat and humidity, I usually just get wet. The rain, in my opinion, feels better than sweating,(and getting just as wet,) under rain gear. I hate to tell you there's no way to keep dry in summer, but it's true. This is the confederacy.