Originally Posted by elcruxio

Probably not sold in the States but me and my SO got ourselves Haglöfs Gram jackets which are very minimalistic and made out the Gore-Tex Active material. I must say, I am very impressed with the material. The jackets have basically no vents and only one small breast pocket and still it remains very breathable even in near 20 degree celsius range. Over that I think I'll just risk getting wet. So far the water resistance has been 100% so even in downpour not a drop got through when my water resistant cycling pants were practically swimming. The hood is also really nice.

Of course exertion level is key here. I can remain almost sweat free when doing my usual commuting pace (which kinda is a bit of race pace since I need to 'win' all the other commuters) while wearing the jacket. With higher exertion levels one would get sweaty even when wearing no clothes but that's a different matter.
It also packs into a Jersey rear pocket nicely.

As a disclaimer, I used to dislike Gore-Tex quite a bit as I used to have a Haglöfs shell jacket with lots of vents and pockets and all that and it felt like wearing saran wrap. Absolutely nothing exerting could be done with that jacket on. BUT the Gore Active is actually really nice.

So, even if you can't find the Haglöfs Gram, aim for something made out of Gore-Tex Active as it's pretty regulated which kind of jackets can be made out of the stuff (goretex specifies that the garments made out of the active stuff need to be extremely minimalistic and lightweight)