It is my experience that two things correlate positively with widespread adoption of biking: a. Relatively flat city terrain. (Not the case in Prague, for example; a lot of the residential areas are at much higher elevation than the city centre.) b. Moderate temperatures at both ends of the summer-winter scale. Most people won't bike to work at -20 or +35 Celsius.
And in regards to cold temperatures, if the only time you daily spend in the cold is the few meters from your house's door to your car's door and then to your work's door, then you just think it is cold because you aren't living it like someone who's active and raises their body temperature in the cold.
Currently I cycle 10km to work and arrive before the sun is barely up, I enjoy those rides, I have good lights on the bike and can use cycling paths on 2/3 of the way. The thing I'm really looking forward to is the snowy days when the world is silenced and cycling though a few centimeters of snow becomes magical.