Your piano is made primarily of wood, a versatile and beautiful material that is ideal for piano construction. However, because it's made of wood, your piano can be affected by humidity. Seasonal and even daily changes in humidity can cause wood parts to swell and shrink, affecting tuning stability and touch.
How does the humidity level affect your piano's tuning? Swelling and shrinking of the piano's soundboard is the most immediate and noticeable effect of humidity changes