Why does my hardwood floor show cracks in the winter?

Why does my hardwood floor show cracks in the winter?

One of the biggest threats to your wood floors during the cold winter months is low humidity. What happens when the humidity drops too low? Your wood floors respond to changes in humidity by shrinking and showing gaps between planks.  In order for the wood flooring to perform as designed, the temperature and humidity conditions inside your home must be kept continuously within a certain range. This range varies slightly depending on the manufacturer and type of wood flooring. Generally, the required range is between 60-80 degrees with a relative humidity range of 35 percent to 55 percent.  Here is a great winter guide from Master Craft.