You won't need the long underwear unless you're spending a significant amount of time outside. Get some nice merino wool socks and warm gloves. Wear a hat that covers your ears and have a scarf to cover your face to protect from any wind chill effects. You will probably want some boots if there's going to be snow. Getting to/from buildings can be messy and the salt can ruin a nice pair of shoes. Just carry your shoes in a separate bag and put them on when you're inside.
Wear layers on top so you can remove something if the building is too warm.
For your reference, for more serious cold:
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