Samuel de Champlain and the original European settlers of Quebec had a very hard time, some freezing to death in the winter. Makes me wonder if they knew about the Gulf Stream and why their winters were milder despite being at a similar latitude to that of present-day Quebec City.
The Jamestown colonists dealt with hardships but of a different kind - but you also had those in New England, where winters are definitely harsher than in Great Britain despite ten fewer degrees of latitude.
If they knew of the fact that water has a high heat capacity and prevailing winds in all of these places are westerly, would they have reconsidered settling places like the St. Lawrence Valley and New England?