My experience is that low temperatures are not a problem for cycling. Precipitations are, be it rain or snow.
If it's -15C and sunny it's good, but if it's +15C and raining it's a pain.
If it's -15C and sunny it's good, but if it's +15C and raining it's a pain.
In the Netherlands and I think even in Copenhagen, 15C and raining is much more common. In my own experience, raining isn't the biggest pain. I hated the wind the most.