I lost around 50 pounds since I started riding so I try and commute almost all the time. It is easy to say it is to cold and I skip a few days a month, usually when it is raining before I leave to go to work. But I keep at it since I am seeing some results. And once I am out there I find that it really isnt to cold with the right clothes.
It is tough this time of the year in pennsylvania too.

. Last night was low 40's and a drizzling rain on the way home.) But since I was at work I had to ride home and it wasnt to bad when I got out and got warmed up.
I have not yet gotten enough motivation to leave to go to work when it is raining but I am working up to that hopefully.