It is important to remember how 'breathable' fabric is rated. Our old friend Goretex, largely accepted as the top rated waterproof breathable fabric out there, only allows a permeation of about 3% under the best of conditions.
Waterproof breathable fabrics are rated at a stated humidity and pressure difference; IOW if the pressure inside the 'rain suit' and the pressure outside the rainsuit (Atmo) are the same the breathability is much less, additionally if the humidity is close to the same inside and outside the breathability plunges even further.
This is why you will sweat in a 'breathable' rainsuit; most of the breathability claims are hype. 3% or even 5% isn't much and you need to really watch your activity level or end up soaked in the $300 'breathable' rain gear. I have touted the benefits of venting over breathability for years, even here on HF. And the fact is that any material that is waterproof/windproof will collect condensation under the right circumstances.
This is true of any 'breathable' waterproof/windproof fabric.Originally Posted by Canoebie
Even my beloved Frogg Toggs have a problem above about 60 degrees keeping me dry from sweat; I really need to put some vent zips in them to be truly effective.