It seems to have a much more ordinary meaning to me - I picture a class of small school children, who have been watching the snow fall from the classroom. Break time arrives and, in their excitement, they all go charging out, with the narrator "following the pack". "Swallowed in their coats" refers to the small size of the children, wrapped up in their bulky winter coats with the scarves of red perhaps being part of the school uniform. The scarves are tied tightly to protect them from the cold, so tightly that it seems that they have been pulled tight to "stop their little heads from falling in the snow". "I turned around and there you go" conjures up images of the narrator, himself a young child in the song turning to throw a snowball at his friend, Michael, who falls as he tries to avoid it. As the snowball hits, Michael suffers a burst nose dripping blood onto the snow. The metaphor of "strawberries in the summertime", to me, shows that while something unpleasant has happened, the boys are having fun and Michael sees this accidental injury as part of the fun, not something to get upset about.