Researchers at Climate Central have put together an interactive map showing what summer temperatures will be like across the US if current emissions trends continue

According to their research and theory, Cities in North Dakota can expect to be 10-12 degrees hotter in the summer at the end of this century than they are now.

This methodology doesn't take into account humidity and dew point, a couple other factors that contribute to how comfortable the heat could be. It also only looks at daytime summer temperatures. It also assumes the levels of Greenhouse Gases in the atmosphere keep increasing through 2080, as they have for the last several decades. The full methodology behind this map can be found here.

Looking at the trends in this map... I think a smart business investment for the next 40-60 years would be sunscreen manufacturers!