During the hottest days of the summer (it very rarely goes above 28C or so - average maximum temperature is around 22C during the hottest summer months in southern Finland), yes, but not that often.

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.