Refuses to pee outside, help!

My dog does his business outside most the time, but will pee on the rug if we're not paying enough attention to his signals (im still trying to learn his signals) but recently its hit the single digits and negatives, and he starts shivering in about 30 seconds and refuses to do his business outside. Its gotten to the point he wont even wake me up to go out (its been his routine for a while). Hes bundled up every time, but he just wont do it