-4° on the ride into work = need for warm clothing. Enter: Sheep hair, aka wool.
If you don't have any mid to high quality wool clothing, I highly recommend it. I have 3 wool shirts that go on in layers depending on the temps - 2 Smartwool long sleeve base layers (one lighter and one heavier) and a regular cheap-ish wool sweatshirt. The wool sweatshirt is of lower quality, so it itches like crazy against the skin. I only bust that out when it's cold enough to warrant 2 layers of long sleevedness; like this morning. I add a cycling vest in between the layers for wind block since wool, by itself, isn't that great at keeping the drafts off my skin.
I'll wear 1 to 2 of these wool shirts all through the week, then wash whichever ones get stinky. Usually, that's only the base layer if I've worn it every day and had a couple warmish rides in there too. There's no way technical fabric base layers could handle that washing schedule. Or rather, no way I (and my I, I mean my nose) could stand being around it for more than 2 days, max. I have mentioned before, that my manly smell can be quite formidable. Wool somehow doesn't hold in as much funk as newer technical fabric. Not sure how it works, but I'll take it. It's much better than going through 5 tech fabric shirts all week and having a pile of stinky laundry by the weekend. Plus it could be cheaper, depending on how much you'd spend on the tech fabrics, versus how cheap you can find your wool. I like to hit up Canfield's sales in Fall for Summer stuff and Spring for Winter stuff.
When the temp drops and whisks away your wharmth, I whole wheartedly recommend you whear your whool. Cool Whip.