Hard to say. Generally pill packages say that temps between 59 and 86F are okay for shorter periods of time. This article from Planned Parenthood says that most medications are actually fine from 32 to 50s F {dafnmDCwi} But also if you can't heat your flat, what's there to do? People live in hot and cold climates and regularly use birth control. When I lived in a hot climate my apartment was often 80F and I didn't have any issues. Personally I'm not too concerned as long as its a temperature that humans can live in. But technically yes, you are supposed to store them at room temperature.
