Water is a byproduct of combustion process happening inside the engine. The chemical reaction of combustion is

This water is in form of vapors as the temperature in the engine is high. In cold weather, these vapors condenses inside the exhaust and start to accumulate in the resonator which then is thrown out with pressure.
Rust-free exhaust does not let the water condensate accumulate and is drained by this little drain hole in the lower section of the resonator (Dholkee)

It will still drip water out of it but it will not be noticeable as it will be draining throughout the driving.
Try clearing the pin hole of a water throwing car, let's see what come out of it...?