The thread title says you are starting in the NW. Oregon/Washington I assume. You could take the northern route cutting thru montana the Dakota's and Wisconsin slicing down thru Michigan. Granted it is the long slow way to get there but far more scenic. The drive across the plains can be hot but any time from June till mid September. It is a roll of the dice. The weatherman can't get it right so when we are planning our trips we just do it and prep the vehicles the best we can and go.
p.s. you are on a rv site where people "like" the driving part. The answers you get will be biased.
