The northernmost french community (of appreciable size) in the world is the remote mining town of Fermont (https://en.wikipedia.org/wiki/Fermont), in Quebec near the border with Labrador. It has ~3000 inhabitants, and is based around a large bunker/building containing housing, shops, schools, etc, which let's people live their lives in the winter without having to go outside.
The second northernmost French community is Dunkirk, France...