Car washing in frigid weather

Would someone know if it is safe for the paint of your vehicle to be washed (at a car wash) when it's been 0 degrees or below outside? I live in New England and periodically run my vehicle through a car wash when it's averaged 30-40 degrees out. But with this frigid cold and the water temperature being very warm, will this affect the paint? Grant it I know the salt and dirt on it now is doing no good but I have no idea how paint reacts to a sudden and dramatic temperature change.