I have to acclimate a bit to heat (over 85°F) and especially humidity, but I never really acclimate to cold. If I'm riding out in the morning and it's expected to get to 68 or 70 in less than a couple of hours, I may go in shorts and short sleeves, maybe arm warmers - sun, humidity and wind can really change the feel of any given temperature. But if it isn't expected to get over 65, it's long sleeves and knee warmers; full Lycra tights and a lightweight base layer below 60, shoe covers below 50 or even 55. I've got wool tights, wool jerseys, a mid weight jacket, and of course a balaclava, but I don't even ride if it's not expected to get over 40. I'm a wuss, I know, but it's so few days I'm exposed to those temps each year that it's not even worth it to me to buy the heavyweight gloves and shoe covers I'd need to ride in cooler temps, or re-adjust my helmet straps to accommodate a wool cap.
Speed comes from what you put behind you. - Judi Ketteler