Obviously, more people vacation during peak season, but there are plenty of people who prefer to travel during the cooler months. Maybe they want to avoid the crowds, maybe they want to take advantage of the lower rates, or maybe they just want a break in the February doldrums.
Knowing who will want to rent your vacation home and then buying based on their demands, rather than just your own family's demands, will make it much easier in the long haul when you want to rent that property out.