When you purchase hardwood flooring from a reputable specialist, you will be warned about what to expect from the floor as it acclimatises to its new environment. While these professionals will always ensure that a floor is fitted to exceptionally high standards, seasonal changes can sometimes affect the floorboards.
The expansion and contraction of the core can happen because of varying humidity levels and this sometimes results in a squeaking sound. However, it may be that the sub-floor is not perfectly flat and so you might need to perform some basic maintenance on the floor to stop this from happening. By waxing the joints between the timber boards, you can ensure that the squeaking noise is reduced or even eliminated.
Wood flooring should always be fitted by an experienced floor layer as they will assess the place where the floor is to be installed and make sure that the sub-floor is perfectly positioned in the first place. They will also recommend ways to maintain the hardwood floor and keep it looking at its best throughout the year, despite fluctuations in temperature and humidity.
If you happen to have an under-floor heating system, this can affect things further and so it is all about managing the environment and keeping the temperature in the room as constant as possible.