Because he obviously lost control of the vehicle...
It does mean that it's cold enough for problems to crop up overnight.
And I can tell you every time it snows I see dozens of people in the ditch from driving to fast for the conditions.
1: Hey could have fell asleep
2: It could be that cold but if the roads are dry there should be no ice
3: You have to know how to drive in different conditions. Just because there is snow on the road doesn't mean I'm going to drive everywhere at 20mph. Any by driving I do include braking.
The point here is we don't know all of the details, but the fact is you can drive 70mph when there is snow on the ground. Like right now where I am at it snowed over the weekend and there is still snow on the ground but the interstate is perfectly clear.