If it's anything like my supra it will just be water in the tailpipe.
Where i live it gets pretty cold and damp during the night, and after a few days there is literally a litre or more of water sitting in the tailpipe, it all seems to catch in the cat converter.
I'll start the car, a puff of blue smoke will come out (just the valve seals, nothing major) then after abit of warming up the white smoke/steam will come pluming out, becuase the exuast heat is evaporating the water that's in there. A good 30min drive gets rid of it all and there is no visible smoke after that.
Usually takes a couple cold nights for it to happen again. I'm thinking off plugging the exuast up during these cold nights.