I was until I wasn't. I commuted by bike and/or mixed mode in the Denver area year-round for a couple of years (6, 36, or 66 miles RT), then year-round in southern California (6 miles RT) then made it a little over a year in Alabama (18 miles RT), got depressed, and drove for about eight months.

Since 2013, I've been year-round, all weather in western Wisconsin, but my commute is a joke (3-4 miles RT). I got rid of the car entirely after a few months. The next commute will be ~19 miles RT in North Carolina. It looks like there are some nice routes, but I'll have a backup vehicle again, so we'll see how that goes.

Violent thunderstorms are probably the biggest deterrent; I can handle most temperatures. Feral dogs and dangerous infrastructure are also a deterrent.