10 C (50 F) is considered warm? 
To people like me, from warm climes, yes, -3.4 is extremely cold! Even 10 is still cold!
No, 10 C is not considered warm. I don't see your point. "Warm" in Sweden would be maybe 25-30 C (77-86 F)
If you consider that warm why would -3.4F not be cold?
Because that's the kind of weather that makes you change your behaviour (removing clothes, going for swims,etc)
But a few minus degrees just means you have to put on a winter jacket. Now, 10 minus or 15 that's harsh. As long as you can survive naked for a considerable time it's not seriously cold.
