The way I had it explained to me way back when everyone was doing the song (having learned it from the Kingston Trio, not knowing it was from a Broadway musical, and thinking it was actually a folk song) was that the fire, Joe, was associated with coffee (a cuppa Joe), which could be a great comfort. All over the internet, I find that the rain is called "Tess," but that seems to be from the KT's interpretation of it (everybody copied it off that and replicated it). I was told that the rain was "test," because the constant drizzle of cold rain down the back of the neck of your slicker could be a real test of your patience, endurance, and general sanity.

As to why the wind is called Mariah, I don't know why she swallowed the fly—

'Scuse me. Wrong song.

Don Firrh