That being said your flat/home insulation plays a huge role. I'm living in Germany for a few years now, when it's 0c outside it's still 18c+ indoor even without any heating in my flat. When I was in California if it was 13 outside it would be 14 indoor, you could feel the air going through the doors'/windows' joints.
edit: to all the people saying I can thanks my neighbours, I pay my share of the heating since it's averaged. I only have one shared wall so I doubt it changes much