Less than an hour, I'd say. A warm summer day can easily be 25-30C, typically 20-25C. That's enough to go to 50C in an hour, windows closed, even on a half-clou

Less than an hour, I'd say. A warm summer day can easily be 25-30C, typically 20-25C. That's enough to go to 50C in an hour, windows closed, even on a half-cloudy day.