Interesting thread. But I tell you, if it were THAT hot (45+ degC) I'd be heading UP to my son's school and sitting in on their classes. They have air-con and we don't at home!
Actually, funny story, kind of related: I was doing work experience with OTIS Elevators and lift wells have to be air conditioned to keep all the electronics safe, even when the entire work site may be still being built around it. I was in a lift well working on some circuit relays and it was a loverrrrrly 24 degC. Outside it was 36 degC. The Union reps were running around the work site with theor thermometers and when it hit the go home temperature, they closed the entire building site, even us in the beeeeeewwwwtiful lift well had to go home. (And then it was onto a train in Wynyard which was HOTTER again.)
Anyway, that aside, I have never heard of schools being closed with heat BUT then again some should be. I have taught at schools that had neither adequate heating or cooling and classrooms were so cold in winter and so hot in summer it was impossible to teach, let alone learn.
If only the money being pumped into computers in schools could be hijacked to just provide the basics!