Your piano is made primarily of wood, which is greatly affected by humidity. Changes in humidity cause wood parts to swell and shrink, affecting the tuning and touch. Eventually, wood will crack and glue joints will fail. This is only the beginning.
An effective answer to humidity problems is to have a humidity control system installed in the piano itself. These systems are designed to maintain the relative humidity of the air within the piano at the ideal level of 42%. The components are installed out of sight, and are easy to maintain.
While not eliminating the need for regular piano maintenance, humidity control will allow more stable tunings as well as help to preserve your piano investment through the years.