I think the other big change is in communication. When i was at school, and dinosaurs stalked the land, the school either had to decide to close at opening time when the children arrived, and even then it might be too late to let some working parents know, or it had to stay open to look after the children who had arrived. I can remember the school keeping a record of whose parents were out at work all day and whose parents would be likely to be at home if the school closed early, also informal arrangements among friends as to who could safely be left at a friend's house because their own parents wouldn't be there.
More than snow, because we lived in London where heavy snow was unusual, I can remember the walking crocs to get kids home when school closed early because of fog which, in the 50's was much heavier than we see nowadays. heavy fog in daylight is bad enough, but heavy fog in winter, after dark with the streetlighting we had then was very unpleasant. There also seemed to be one or two "chesty children" in each class who were not allowed out of the house on foggy days which you don't hear of now. The good old days? tell me about it!