Not having this problem in Georgia, I can only offer the advice from my friends in the great white north.
Use hot water from the house. It will take a while longer than summer, but that's how they do it. I'm guessing they use a suds bucket, and a second (and possibly third to wet the car rather than the hose.
2002 BMW 530i
1997 Ford Mustang GT
1995 Honda VFR 750 (For Sale)
1964.5 Ford Mustang