Machines don't care about the Heat Index, only true temperatures. Heat Index combines temp and humidity into a value of how it feels to us humans. It could be 90F with 80% relative humidity and the heat index would be 113F.
On my return trip it hit 93F and the generator didn't stop for 11hrs running everything, so that was good. I hope it was just an unusual set of circumstances that caused it to overheat. Dirty, Wind direction, etc. I'm still going to go Onan on the next rig but it will probably be diesel.
2009 Georgetown 350TS (bunks)
400W solar, 440AH 6V GC2
2009 Ford Edge AWD Ltd towed
2011 Honda Fit Sport towed