Temperature, Humidity, And Your Piano

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As the weather cools and heaters rumble to life, it’s worth taking some time to discuss how changes in temperature and humidity affect your piano. Pianos are sensitive to any changes in climate, including seasonal changes. Not taking this into account in the placement and care of your instrument could take years off its life.


Humidity is perhaps the most important environmental factor to consider in regard to the care and maintenance of your piano. Pianos are mostly constructed of wood, and wood swells and contracts in response to the amount of water vapor in the air, otherwise known as humidity.

Relative Humidity

There are three categories of humidity, but the one that is most relevant to piano care and maintenance is called relative humidity, or RH. RH is the ratio of the amount of water vapor present in the air to the amount of water vapor the air can hold at a given temperature before it is saturated. It is expressed as a percentage. For example, a RH level at or near 100% is a heavy fog. Whenever a weather forecast presents humidity as a percentage they are actually referring to relative humidity; humidity is an umbrella term that includes different subcategories.

Your piano will be grateful to you for knowing the range in which to keep the RH in your home. Pianos like a RH level of between 40-50%. If the RH is too low the wood in the piano could shrink and crack, and if it is too high the parts will become sluggish. You can use a device known as a hygrometer to measure the RH level.

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A bridge in a Steinway M. Parts like this can be damaged if the piano is not kept in the proper environment.

Temperature and RH

The amount of water vapor it takes to saturate the air depends on its temperature. Hot air holds more water vapor, while cold air holds less. This is why a glass of cold water will develop condensation on a hot day. The air close to the glass is cold, which means it becomes saturated more easily than the hot air surrounding it. The excess water vapor near the glass converts to liquid water and clings to the side of it.

This becomes vital to understand in regard to the health of your piano when heating and cooling systems are thrown into the mix. For example, when you flip on the heater on a cold day, you dramatically decrease the RH in the area closest to the vents. This happens because the hot air coming out of the vent requires more water to become saturated, so water vapor that is present in that area drops in terms of a percentage of what is required to saturate the air.

Since the RH of the areas near vents is so volatile, it is always a good idea to keep your piano away from vents.

Creating The Best Environment For Your Piano

Now that you have some understanding of the relationship between temperature and humidity and how they affect your piano, here are a few tips to help you create the proper environment for your instrument:

  • Keep the piano away from vents. I’ve mentioned that and highlighted it twice because this is the most basic thing you can do for the health of your piano and many people seem unaware of it.
  • Do not place the piano against an outside facing wall. The air adjacent to a wall that faces outside will typically be either warmer or cooler than the air in the rest of the home, depending on the weather.
  • Keep the piano out of direct sunlight. Direct sunlight will increase the temperature of the piano and warp the wood. It will also damage the finish.
  • Keep the RH level in the room the piano is in as stable as possible. Drastic fluctuations in humidity will cause the parts of the piano to shift constantly which will keep the piano from performing well.

Seasonal Maintenance

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Tuning pins in a Steinway M.

The largest shifts in humidity are usually associated with seasonal changes. In addition to affecting the parts of your piano and how they function, these changes will also affect the tuning. As the wood loses moisture in the dry months of winter it will contract and cause the tuning to go flat. The opposite is true in humid summer months.

This is why technicians will recommend that you have your piano serviced at least twice a year. The best time to have your piano tuned and/or regulated is a few weeks after you turn on either your air conditioner or heater. Wait for the environment to stabilize, taking into account the changes in humidity you see on your hygrometer.

Key Concepts

The most important concept to take away from all this information is that the RH level of your home will have a dramatic effect on both the tuning of your piano and the function of its parts. If you do your best to create the optimal environment for your instrument and have it serviced at least twice a year by a professional technician, you can keep it singing all year long and add years to its life.