It does if you are moving to get away from another group who perceives you as an enemy, or has superior weaponry and wants the spot where you happen to be living at the time.
The spread of migration in the Americas shows the leading group as very primitive, with "technologically superior" waves pushing them along. Compare the "indigenes" of Tierra del Fuego with the Eskimo. Very similar climatic conditions, very different technology level.
It also makes sense if the culture is already cold adapted, and the glaciers continually melt their way back into the oceans, freeing up new lands to the north. :^)