Are many of the exhibits inside with air conditioning, or is it mostly outside? Wondering if this is a good museum for a very hot day.

Most exhibits are indoors, including the space exhibit across the street, the historic red Barn, kids areas, and the main museum (SR71 area), really just the large jetliners 747, 787, Concord, ww2 bombers, that are outdoors, and those still under shaded roof. Excellent place for a hot day

Except for the hangar where several airplanes are parked, the rest of the exhibits are indoors and have air conditioning.

Except for the big airplanes most of the exhibits are indoor and even the out door exhibits are very breezy.

Yes, there is a lot. But the kids are probably want to go outside and see the HUGE airplanes.