In hot weather I do sweat under the rain gear, but the trade-off still favors wearing the gear versus getting wet from the rain (for me). One must ride more slowly.

I used to have some yellow pants and jacket, a lightweight material, $25 each. They worked, but they would tear and I would have to repair them with yellow duct tape. Now I have Columbia rain pants that cost around $90 as I recall, and they are better BUT, at one point about a year after I got them they seemed to lose their waterproof-ness. I washed them with some cleaner made for that type of fabric, and washed them again with some waterproofing substance (got both at REI) and that seemed to restore them. The jacket is Showers Pass and I am happy with it.

I will say that if I had a day of 90 degree temperatures plus a heavy rain, things would not be so nice.