I am going to be driving from San Jose, Ca to Austin, Tx on Aug 1st. Is there any reason I should avoid the fast route of going through S. Arizona. It might be 110 degrees.
I assume you are taking I-5 south to I-10 east in Los Angeles. No reason to avoid the route. I am living with that high temp on a daily basis during the summer... Make sure that your engine compartment fluids are correct and that your tires are properly inflated and have sufficient tread depth, prior to starting your trip.
DON'T DO IT!! YOUR BATTERY WILL EXPLODE!!! Nah.. there are probably good reasons to avoid S. Arizona but it has nothing to do with your Prius. haven't you seen Breaking Bad?
Just crank up your AC. I just arrived in Vegas from Los Angeles. It was 102-113F throughout the 15 freeway. My AC was set on medium/75 degrees, and there was no battery fatigue, not even on the 16mile climb of death after Baker. Car was traveling 65-70 MPH. When the HV battery is cool, nothing can stop the mighty Prius, not even high temperature and 239k on the engine...love this car.