This is something that’s puzzled me for a while, though admittedly I haven’t run through all the possible explanations. One would be cabs, but that doesn’t make sense especially for people going into Manhattan. Taking a cab might keep you dryer since you only have to walk to and from the cab, but driving in the rain has gotta suck. I understand that when I get to work sometimes people take a while getting in because their various commutes could’ve been delayed by the rain, but the half empty (or half full?) subway cars I don’t. Could it be all these people are saying “screw it, I’m staying home where it’s dry.” I’m sure there’s a perfectly logical explanation that’s just passing me by, but I can’t think of anything else.