In Central Florida, it's 90*F by mid-day. The inside of a closed car reaches 110*F in about an hour. Dew point is in the mid-70s.
We transport our cameras from the house to the car and back in zipped-up freezer bags in an effort to try to reduce the effects of changes in dew point [sic humidity]. We get-up early and go shooting, then go to work weekdays or chase chores on the weekend.
We know that we shouldn't leave kids or pets in a closed car, but what about our cameras when we move on to other activities? Is it smart to leave a DSLR in the closed car? [We can't crack the windows of the car for fear of it becoming a 'lizard house.'] If not, what should we do? We're thinking about a cooler and not using those 'blue freezer block' things.