It’s definitely a good idea to bring layers. In the US (at least in the NY area), people tend to keep the heat on very high in the winter (not sure why people want to be hotter in the winter than in the summer, but whatever..), so if you dress too warmly, you’ll be too hot inside.
So the best is to wear an outfit that’s not too warm with layers on top for outside.
Even though most people aren’t wearing coats yet, I would suggest you bring one for the following reasons:
1. The weather changes from day to day, and there have been “coat days”.
2. You’re used to warm weather and get cold easily.
3. Best to be prepared.