Hardwood Floor Buckling
Diagnosis for floor buckling requires some photographs. Also requires a description of the exact method of floor installation, i.e. nails, staples, glue. Also what type of hardwood, was it traditional 3/4 inch thick boards, engineered lumber, or glue down squares. What type of subfloor, plywood, particle board, OSB, pine planks?
Floor buckling is usually moisture related, since wood expands perpendicular to the grain as relative humidity increases. Since relative humidity is higher in the summer, at least where you live, wood expands in the summer, and shrinks in the winter. The subfloor may expand at a different rate, depends on the type of subfloor, and method of installation.
The usual method to minimize buckling is to provide an expansion gap around the perimeter of the room. The American Hardwood Flooring Association has specific recommendations for the required gap, which varies by species. If you have too small a gap, the hardwood is likely to buckle in the center of the floor in the summer as moisture in the house increases.
I have an oak floor in MA, which buckles at the center of the house usually starting in late June, then goes back to normal in the winter. Probably too small a gap around the outside of the house. A dehumidifier would help, but I don't care to pay the electric bill for such a device, so I live with it.