-9*C is considered here to be a warm winter weather
I live in the middle part of the European Russia, it is not Siberia, and we do not have extremely cold winters here. So, -40*C is very-very rare, but theoretically can happen. The normal winter temperatures in my area are -15*C - -20*C. When it comes above -10*C, it's warm already
We can have a few weeks (in total) per a winter period with temperatures below -20*C, and -30*C is really cold.
And it's very rare when we have below -30*C, but sometimes we do. 2-3 years ago we had -39*C in January, it was the lowest point per the recent decade as I remember.