Hi,
In the years I was heavily invested in Kansas City I sold and rented properties all year round, of course things slow down between Thanksgiving and New Years Day. I never saw someone move when it was actually snowing, but I saw a lot of people move with snow on the ground.
I think most people would prefer not to move in cold, cold weather, I think people do what is necessary for them to do including move when necessary. Now granted the statistical numbers of people buying or moving in winter may be half of the people who move in summer there is in fact some number of people forced to make a move!
GR