Yu1208I'll copy my comment from above:
I wore it for the first time in 'cold' weather today (~55F, 13C). I live in a windy city as well, so this was a perfect day to test.
I wore a button down shirt, an undershirt and the K-Way. The K-Way did a great job blocking the wind, which was the biggest contributor to keeping me warm. I wouldnt say the jacket keeps you warm, but it does create a great seal, which can keep you warm. If it were any colder, I'd probably wear a cardigan underneath.
Bonus Note: This thing is close to form fitting so if you are planning on wearing it in colder weather, i'd grab the next size up so you can fit a fleece under there