Methane rain...
...such a strange little world. Back in the 1970s some early IR observations suggested the surface temperature was ~200 K leading to a model of Titan with a 21 bar N2 atmosphere to make a sufficiently warm greenhouse. Of course now we know they were being misled by Titan's warm stratosphere (~170 K) but it's still a valid atmospheric model. The weird weather that would cause is hard to predict - imagine an ammonia/water ocean with ammonia rain and water snow...