Question: Last night, I walked home from my bus stop (in Belgium). Since it was around 11 PM, it was quite cold, probably only about 4-5 °C. However, it didn't actually feel cold at all, and I didn't feel like I had to rush to get home for the cold. In fact, I didn't have headwear on, but I didn't get cold ears. It was about the same temperature as this morning, but the difference is that this morning felt a lot colder, probably due to the wind and drizzle.

I tried to describe it in English on Twitter, but I couldn't actually find a proper word to decribe it. I considered "a warm cold" or "a cozy cold", but I thought these were too poetic, more like something you'd use in a fairy tale than in a tweet to a handful of followers.

How can you describe that temperature without it becoming confusing or poetic?

Answer: 
"Real Feel" is the word which is used in accuweather. Usually morning is more colder than nights beacuse in morning we are coming out of "warm home" and till night we become used to.
Technically, the condition is produced by low humidity and lack of wind. I would suggest using something like "frosty stillness". Also, if you are under trees, you can pick up infrared radiation from the trees themselves that actually does warm you. In that case, you could mention the trees, such as "the warm embrace of trees in the frosty night".