Depending on your geographic location, autumn may smoothly transition to include cooler temperatures, less sun, and stick figures trees, sadly lacking foliage. However, there are two places I have first-hand knowledge of that, although polar opposites both provide stark reminders of how cruel winter can hit.
First, as I sit in my cardigan from my couch in downtown Boulder, looking at the foot of snow we’ve just received overnight, I am reminded that winter is upon me. In the Front Range winter comes on very suddenly, jolting you out of a colorful and mild fall. I was in shorts outside only a few days ago and now I am in shorts again…but on a trainer. Bam: winter overnight. This rapid transition does not seem to slow down people commuting to work, however. I witnessed a myriad of people, on every imaginable type of bike, riding in the snow (minus any TT bikes, which would be horribly unwieldly). Funny fact, I did not see anyone on a fat bike in the snow, though. Riding in snow can be both a little tricky and downright fun. For some tips on how to handle this adversity, check outPeople for Bikes.
Second, central Arizona is a hot bed for winter cycling, both literally and figuratively; images of deserts and warm sun dance through my mind. One drawback: have you ever been in a desert at night? It is freaking cold compared to the day. Somehow, temperatures in Tucson and Phoenix can be down in the 30s in the early morning. This constitutes full on wool clothing, lobster gloves, and your warmest base layers, which conjure conditions (and chilly memories) more akin to Colorado.
The big difference between the two is that I am still riding, in my shorts, in Boulder; we just had to skip some of the wool-weather riding. Do not misunderstand me; we do have cool days here that dictate more substantial gear. The key point is that while we may have some seriously inclement weather here in Boulder that may prove dangerous, there are still gorgeous days sprinkled in between, which you can find very pleasant in your shorts and for central Arizona, though some mornings may be chilly, you can always have a blast outside.