I am surprised Banerjek didn't partron this thread.
He would have suggested gore tex active shell jacket like this one: http://www.amazon.com/Gore-Oxygen-Go...dp/B007AN992A/

gore-tex is semi breathable, and active shell is light enough. the jacket is windproof/waterproof on the front and breathable on the back because that part is not polyester, so your sweat doesn't accumulate. Might be worth a try.