Winter Temperatures and Norwegians:

[KamaAina]

24. "Every Norwegian knows at least four languages, and three of them are Norwegian."

http://en.wikipedia.org/wiki/Norwegian_language

From the 16th to the 19th centuries, Danish was the standard written language of Norway. As a result, the development of modern written Norwegian has been subject to strong controversy related to nationalism, rural versus urban discourse, and Norway's literary history. Historically, Bokmål is a Norwegianised variety of Danish, while Nynorsk is a language form based on Norwegian dialects and puristic opposition to Danish. The now abandoned official policy to merge Bokmål and Nynorsk into one common language called Samnorsk through a series of spelling reforms has created a wide spectrum of varieties of both Bokmål and Nynorsk. The unofficial form known as Riksmål is considered more conservative than Bokmål, and the unofficial Høgnorsk more conservative than Nynorsk.

So the Norwegian spoken by the settlers in Minnesota would likely have been closest to Riksmål.