If you have a forced-air furnace system with a humidity control, this is the ideal situation and you can successfully do floors at any time of year. Because wood expands and contracts with changes in humidity, the use of the humidistat kept between 35-45% will minimize this movement. If you do not have a humidistat, then the contraction of the wood is most noticeable in the winter when the air is dry. The resulting gaps in the joints of the boards will close up again in the summer months when humidity is slightly higher. It is for this reason that you are probably better off installing hardwood in the winter when the pieces of wood are at their minimum dimensions, they’ll go together tightly when they expand in the summertime. They should go back to their original positions, without much indication of movement to occur. Sometimes gaps result in some of the joints that do not completely go away. This is not the fault of the installation or a defect in the material, but a normal condition of the behaviour of wood.
What is the best time of year to do our floors?