I prefer summers, no doubt. When I lived in Az, I commuted year round (20 miles each way) almost every day.
Here in Everett, it's been a spectacular summer, and I admit I'm spoiled. I'm getting a larger bag around the beginning of Oct, to accommodate my additional layers/bulkier gear. Probably by the end of the year, I'll get a fairing, and possibly a full aero sock (I commute on a recumbent). I am a bit of a wuss when it comes to cold (see above...Az blood.
) I will keep riding though, as long as there isn't much chance of actual ice or snow on the roads. When it gets bad enough that I'll start needing 4 wheels more than a couple times a week (hopefully not more than a few times this winter), I'll take up swimming at the gym to keep my cardio up.