The 10-year old hardwood floor in my house gets small gaps every winter from the dry climate. Does this mean if I install hardwood floors (in another room) in the winter - the boards will push together and buckle in the summer because of the humidity? ie Should I wait until spring to install (I'm in NC avg. low right now is mid thirties).
The key to avoiding the problem of buckling is acclimation (as mentioned by Bob), proper installation using manufacturer approved techniques, and installation using a manufacturer recommended gap around the edges. The gap is covered by molding, the required size of the gap depends on the size of the floor, type of wood, and relative humidity variation anticipated over the course of a season. There is very little you can do to prevent gaps in the winter short of humidifying the house, however gaps add character to the floor. Buckling on the other hand is serious trouble, and is avoided through proper design and installation.