Most of my ancestors came to this country very early, and while the climate they came from differed little from what they left weather wise that is. The political climate changed a lot from the old world to the new world.
When my grandfather came from Denmark, he settled in Minnesota, actually colder than where he lived in Denmark, but once again the political climate was a big help in his decision to leave Denmark. My grandfathers oldest brother disappears about the time Denmark lost the Schelsvig Holstein region to Prussia, and Denmark was threatening to go to war again to get that area back, so 5 Hansen brothers left Denmark a few months before they were to be drafted, and I think there is some evidence one sister also left. The other reason was probably the fact that the Hus that my great grand father owned was probably not large enough to support the 5 brothers and their families so they emigrated to the USA. According to my research a Hus was usually about 5 acres, and probably not enough for one family, but my great grandfather was also a tailor, so his ten children probably did not go hungry. Actually only 8 survived to adulthood, 6 boys and 2 girls.
Once in Minnesota 4 brothers never left Minnesota, four did move further north from where they settled after coming to the USA.
Of the five that settled in Minnesota only my grandfather left Minnesota, and I really never got an answer to why he left Minnesota. I asked my dad why they left Minnesota, but he was only three when they moved to Montana and did not know why. My dad's older brother wrote an autobiography for his kids and grand kids and he said they left Minnesota for Montana because it was warmer in Montana. It may have been a little warmer from where they were living in the northern part of Minnesota near Sebeka to the southern part of Montana at Columbus, but I really think it was because my grandmothers aunt lived in Columbus and had a job lined up for my grandfather. He ran the creamery, delivered milk and cream and butter door to door. In the 1920s they moved to Blanchard, Idaho and that was much warmer than Montana or Minnesota. My father said my grandfather had a wonder lust, the grass was always greener somewhere else, so that probably played a more important role in the moves that made than the change of climate.