Once it hits about fifteen degrees things get pretty miserable. Not to derail the convo either, but I will say, investing in a proper set of baselayers and a windproof jacket will really help out whenever it's super cold outside. Most people who wear cotton--t-shirt, hoodie, longsleeve, whatever--next to their skin put themselves in a pretty crappy position as soon as they begin to sweat because that material soaks up moisture and keeps it close to your skin, which, in turn, makes you pretty damn cold. Add in a top layer that allows wind to penetrate, and you're basically screwed 'cause that cold air is going to push right through to your core, cool down that layer of sweat even more, and your body is pretty much robbed of any insulation it may have worked to create.