The inside of my apartment peaked at 28°C when it was 40+°C outside. No AC. While that is still a little uncomfortable, I can power through that it it's just a week or two a year and blast a fan, and take a cold shower or two. As for some window-mounted (temporary) AC, no chance, I'd have to get permission to "build" it from the city first, which I won't unless it's a really good permanently installed one (so it cannot fall and hit somebody) aka "major" construction, and then from my landlord too.