Croatian Shepherd has an undercoat and a top coat, so it's fairly well protected against cold.
-2 °C is not a problem in itself for that kind of a coat. It's the wind-chill that causes dogs to freeze to death.
Snow itself is actually a warming layer, so it's fine.
Just don't let him stay outside for too long during blizzard and he will be fine.
From experience, neighbor's dog was surviving outside in his wooden den just fine until the blizzard hit at -25 °C. The wind-chill must have been below -35 °C. He froze to death that night. Note that it was -25 °C the whole week and he was fine. It's the wind-chill of the blizzard that killed him despite being around five years old and otherwise in good health.