While NYD works outside, I would be quite surprised if he would not be interested in doing some work for you in a heated space you have access to. Your garage, a friends garage, a storage facility, workshop, what have you.
Some days due to really cold weather I can not detail cars, It is just to cold and not worth it. But on a typical winter day it is cold but once i keep moving after a while the jacket comes off and i am detailing wearing a fleece.
I had bronchitis about 10 times and numonia 2 times.
because when i use to live with my parents, i would wash the car when it was borderline freezing out, and the driveway would turn into a skating rink. Not fun