My husband and I made a trip from our home in SoCal (San Diego County) to Orlando FL, then up the east coast to NJ, back in summer 2012. The weather: hotter than Hades in the deserts of CA, AZ, NM and TX (as you might expect). Humid as could be in the rest of the states. We came home via MO, KS, CO, UT and NV.
Here's that trip report, if you'd like to look it over.
Donna