I usually wear the baby, cause then he also keeps me warm
General DC winter day, I put him in socks, pants, a long sleeve onesie, and then one of those bunting things that make him look like a bear, and goes over his feet and hands.
The other day when it was 25 degrees out, I added a second hat under the bunting hat, and a pair mittens under the bunting hand flaps.
His cheeks are cold, but he's otherwise nice and cosy, and we're usually out for 30-45 minutes.