Is my piano out of tune?

For orchestral or concert performances, pianos go slightly out of tune by intermission. Typically, piano tuners walk on stage during the 15 minute break and make very slight adjustments to the tuning. If pianos go very slightly out of tune in this time period, imagine how far out of tune they go in a few months!

Humidity has a great effect on piano tuning stability. At one outdoor concert in summer time, a piano had to be pitch lowered to A=440 after the soundboard had absorbed too much humidity and the piano was too high in pitch. The next day, the tuner had to lower the pitch of the piano AGAIN because of excessive humidity. In this example, the piano went out of tune severely in one day because it was placed in an outside environment.

Temperature also has an effect on piano tuning stability. Many people have heated floors in their homes. Unless the soundboard is protected in some way or unless the piano has a humidity/temperature control system installed, the piano will go out of tune. Typically, the soundboard gets 'cooked' by the heat from underneath (or from floor board heaters), and the soundboard slightly flattens, causing the pitch to drop below A=440.

Moving the piano (very carefully in a humidity/temperature neutral environment) actually has very little effect on the tuning of the piano. I've read documentation that is almost 100 years old by other piano tuners saying exactly the same thing. For some reason, moving is associated with tuning instead of tuning the piano a minimum of 2 times per year - every year - with overall maintenance.

Is my piano at pitch?
Just because your cell phone/tablet/computer says A=440 when you measure that one note on your piano, doesn't mean the entire piano is in tune. Many notes can be wildly out of tune. Please refer to my first post above, with regard to pianos going slightly out of tune by the time of a performance intermission for more information.

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