I use the affordable showers pass Storm jacket for its portability. Can fit in a jersey pocket or bottle cage. I typically wear a wicking layer underneath as my arms tend to get clammy and I never use it in any temps above 55f here in TX. Has pretty large vents in the back.

In my experience, hard efforts will mean increased sweat when using any material that is waterproof. You almost have to choose if you'd rather be soaked by the rain or your own sweat.

Showers Pass Elite Pro WILL fold down into its own pocket and is packable. very light, good venting, fabric is breathable and waterproof.

https://www.showerspass.com/products...FU-BswodDugL1w