Now start building up your outerwear. Find a light vest that you'll be able to store in a carry-on if necessary. The Uniqlo down vests fold down to be almost paper-thin. Alternatively, if you already have a quilted vest, that's an equally solid option.
Add a jacket for your final layer of outerwear. If you're heading from the Northeast, you'll be toasty warm when you leave and can easily get back down to t-shirt and jeans when in no-time upon landing. Just throw the extra layers in your carry-on.
Sitting in a confined space for several hours isn't fun. One trick I've learned over the years is to pack a pair of clean socks in your carry-on. After the security check-in, the waiting and the boarding, your feet have been through a lot. Changing your socks mid-flight gives you and your feet a new lease on life—a happy lease on life.